Domestic Rate Loans Fed Funds Effective Rate Overnight Index Swap Rate [Member] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Aggregate Intrinsic Value [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Aggregate Intrinsic Value [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Aggregate Intrinsic Value Statistical Measurement Statistical Measurement [Domain] Share repurchase program, remaining authorized, amount Share Repurchase Program, Remaining Authorized, Amount Components of Lease Expense Lease, Cost [Table Text Block] Thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Five Net decrease in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Director Director [Member] Summary of Future Minimum Lease Payments Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Other current liabilities Other Liabilities, Current Trading Symbol Trading Symbol All Trading Arrangements All Trading Arrangements [Member] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Non-NEOs Non-NEOs [Member] Calculation of Basic and Diluted Net Loss Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Share-based compensation arrangement by share-based payment award, award vesting period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Fixed coverage charge ratio Line Of Credit Facility, Fixed Coverage Charge Ratio Line Of Credit Facility, Fixed Coverage Charge Ratio Beginning balance Ending balance Accounts Receivable, Allowance for Credit Loss, Current Accrued compensation Increase Decrease In Accrued Compensation Increase decrease in Accrued compensation. Class A Common Stock Common Class A [Member] Pay vs Performance Disclosure [Line Items] Line Of Credit Facility [Table] Line of Credit Facility [Table] Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Accounts receivable Increase (Decrease) in Accounts Receivable Operating lease liabilities Increase (Decrease) in Operating Lease Liability Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Proceeds from the exercise of stock options Proceeds from Stock Options Exercised Award Timing Disclosures [Line Items] Other Performance Measure, Amount Other Performance Measure, Amount 2028 Finite-Lived Intangible Asset, Expected Amortization, Year Three Leases Lessee, Operating Leases [Text Block] Common stock, shares outstanding (shares) Common Stock, Shares, Outstanding Operating lease cost Operating Lease, Cost Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] Basis of presentation and summary of significant accounting policies. Capital V LLC [Member] Capital V LLC Shares remained available for grant Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant Long-term portion of operating lease liabilities Operating Lease, Liability, Noncurrent Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Deferred revenue Contract with Customer, Liability, Current Plan Name Plan Name [Domain] Secured Overnight Financing Rate Secured Overnight Financing Rate [Member] Secured Overnight Financing Rate Issuance of Class A common stock related to vesting of restricted stock units Stock Issued During Period, Value, Employee Benefit Plan Other assets Other Assets, Noncurrent Entity Tax Identification Number Entity Tax Identification Number Leases [Abstract] Leases [Abstract] Gross Amount Finite-Lived Intangible Assets, Gross Schedule Of Finite Lived Intangible Assets [Table] Intangible Asset, Finite-Lived [Table] Repurchase of treasury shares in connection with the taxes paid related to net share settlement of equity awards (shares) Treasury Stock, Shares, Acquired Antidilutive Securities, Name Antidilutive Securities, Name [Domain] Issuance of Class A common stock in connection with equity-based compensation plans (shares) Stock Issued During Period, Shares, Employee Benefit Plan Operating Segments Operating Segments [Member] Supplier Supplier [Domain] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Treasury Stock Treasury Stock, Common [Member] Loan Agreement Loan Agreement [Member] Loan agreement. Plan Name Plan Name [Axis] Equity Components Equity Components [Axis] Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] Award Timing Method Award Timing Method [Text Block] Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Accounts Receivable, Net of Allowances Accounts Receivable [Policy Text Block] Minority Interest [Line Items] Noncontrolling Interest [Line Items] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Exercise of stock options (shares) Stock Issued During Period, Shares, Other Insider Trading Policies and Procedures [Line Items] Use of Estimates Use of Estimates, Policy [Policy Text Block] Stock-based compensation included in capitalized software development costs Share-Based Payment Arrangement, Amount Capitalized Total operating expenses Expense incurred Costs and Expenses Ownership Percentage Ownership Interest Percentage Ownership interest percentage. Adjustment to Compensation, Amount Adjustment to Compensation Amount Aggregate Intrinsic Value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value Payables and Accruals [Abstract] Payables and Accruals [Abstract] Compensation Amount Outstanding Recovery Compensation Amount Supplemental disclosure of non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Entity Small Business Entity Small Business Developed technology Developed Technology Rights [Member] Accrued Liabilities Accounts Payable and Accrued Liabilities Disclosure [Text Block] Company Selected Measure Amount Company Selected Measure Amount Remaining contractual obligation, short-term leases Short-Term Lease Commitment, Amount Tabular List, Table Tabular List [Table Text Block] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Accounts Payable and Accrued Liabilities Accounts Payable And Accrued Liabilities Current [Member] Accounts payable and accrued liabilities current. Sales and marketing Selling and Marketing Expense [Member] Repurchase of stock related to the stock repurchase program Stock Repurchased During Period, Value Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Summary of Changes in Allowance for Doubtful Accounts Accounts Receivable, Allowance for Credit Loss [Table Text Block] Lessee Lease Description [Line Items] Lessee, Lease, Description [Line Items] Accrued liabilities Total accrued liabilities Accrued Liabilities, Current Total shares excluded from loss per share of Class A common stock—diluted (shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Summary of Effect of Changes in Ownership Interest in Viant Technology LLC on Equity Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table Text Block] Credit Facility Credit Facility [Domain] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Accounts and Financing Receivables [Table] Technology and development Technology And Development Expenses Technology and development expenses. Unrecognized stock-based compensation expected to be recognized Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Current assets: Assets, Current [Abstract] Goodwill Goodwill Supplier One Supplier One [Member] Supplier one. Consolidation Items [Axis] Consolidation Items [Axis] Repurchase of stock related to tax withholdings on vested equity awards Payment, Tax Withholding, Share-Based Payment Arrangement Authorized amount, stock repurchase program Share Repurchase Program, Authorized, Amount Treasury stock, shares (shares) Beginning balance, treasury stock (shares) Ending balance, treasury stock (shares) Treasury Stock, Common, Shares Summary Ownership of Viant Technology LLC Schedule Of Noncontrolling Ownership Interests Table [Table Text Block] Schedule of noncontrolling ownership interests. Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Employee Stock Option Share-Based Payment Arrangement, Option [Member] Short-term lease cost Short-Term Lease, Cost Vested (USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Depreciation Depreciation 2026 Lessee, Operating Lease, Liability, to be Paid, Year One Supplier Three Supplier Three [Member] Supplier Three Preferred stock, shares outstanding (shares) Preferred Stock, Shares Outstanding Name of each exchange on which registered Security Exchange Name Debt instrument, basis spread on variable rate plus margin Debt Instrument, Basis Spread on Variable Rate Award Type Award Type [Axis] Exercised (USD per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Property, equipment, and software, net Total property, equipment, and software, net Property, Plant and Equipment, Net Total liabilities Liabilities Noncontrolling interests Equity, Attributable to Noncontrolling Interest Common stock, par value (USD per share) Common Stock, Par or Stated Value Per Share Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] LTIP Long Term Incentive Plan [Member] Long Term Incentive Plan. Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Remaining Weighted-Average Useful Life (years) Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life Revolving Credit Facility Revolving Credit Facility [Member] Expiration Date Trading Arrangement Expiration Date Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Current portion of operating lease liabilities Less: Operating lease liabilities, current Operating Lease, Liability, Current Total Shareholder Return Amount Total Shareholder Return Amount Common stock, shares issued (shares) Common Stock, Shares, Issued Entity Entity [Domain] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Senior secured revolving credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Concentration risk, percentage Concentration Risk, Percentage Income before income taxes Income (Loss), Including Portion Attributable to Noncontrolling Interest, before Tax Computer equipment Computer Equipment [Member] Class of Treasury Stock Class of Treasury Stock [Table Text Block] Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Less: Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total property, equipment, and software Property, Plant and Equipment, Gross Exercised (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Common stock, shares authorized (shares) Common Stock, Shares Authorized Cash paid for acquisitions Payments to Acquire Businesses, Net of Cash Acquired Diluted (shares) Weighted-average shares of Class A common stock outstanding—diluted (shares) Weighted Average Number of Shares Outstanding, Diluted MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Remainder of 2025 Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year Numerator Net Income (Loss) Available to Common Stockholders, Basic [Abstract] Total stockholders’ equity attributable to Viant Technology Inc. Equity, Attributable to Parent Treasury stock, at cost; 1,585,349 and 1,565,373 shares held Treasury Stock, Value Lessee operating lease renewal term Lessee, Operating Lease, Renewal Term Property, Equipment and Software, Net Property, Plant and Equipment Disclosure [Text Block] Accrued compensation Accrued Salaries, Current Purchased software Software and Software Development Costs [Member] Concentration Risk Type Concentration Risk Type [Domain] Write-offs, net of recoveries Accounts Receivable, Allowance for Credit Loss, Writeoff Accounts receivable, net of allowances Accounts Receivable, after Allowance for Credit Loss, Current Granted (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross Other liabilities Increase (Decrease) in Other Operating Liabilities Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Document Fiscal Period Focus Document Fiscal Period Focus All Executive Categories All Executive Categories [Member] 2027 Finite-Lived Intangible Asset, Expected Amortization, Year Two Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Weighted-Average Remaining Contractual Term (years) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Assets Assets [Abstract] Expected dividend yield assumption Expected dividend yield Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Document Type Document Type Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Viant Technology Inc. Viant Technology Inc [Member] Viant Technology Inc. Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations Vested (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Summary of Estimated Future Amortization of Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Risk-free interest rate Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Maximum Maximum [Member] Amortization of intangible assets Amortization of Intangible Assets Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Intangible assets, net Net Carrying Amount Finite-Lived Intangible Assets, Net Antidilutive Securities Antidilutive Securities [Axis] Accounts payable Accounts Payable, Current Accounting Policies [Abstract] Liabilities Liabilities [Abstract] Leasehold improvements Leasehold Improvements [Member] Expired (USD per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price Summary of Assumptions used in Black-Scholes Model to Determine Fair Value of Nonqualified Stock Options Granted Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Current Fiscal Year End Date Current Fiscal Year End Date Total lease cost Lease, Cost Statistical Measurement Statistical Measurement [Axis] PEO Name PEO Name Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Award Type Award Type [Domain] Name Outstanding Recovery, Individual Name Disaggregation Of Revenue [Line Items] Disaggregation of Revenue [Line Items] Variable lease cost Variable Lease, Cost Operating lease weighted average incremental borrowing rate Operating Lease Weighted Average Incremental Borrowing Rate Operating lease weighted average incremental borrowing rate. Exchange of Class B common stock for Class A common stock Stock Issued During Period, Value, Conversion of Units Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Over-time revenue Transferred over Time [Member] Money market funds Money Market Funds, at Carrying Value Supplier Concentration Risk Supplier Concentration Risk [Member] Non-PEO NEO Non-PEO NEO [Member] Title and Position [Axis] Title and Position [Axis] Additional Paid-In Capital Additional Paid-in Capital [Member] Allocation of equity to noncontrolling interests Stock Issued During Period Value Allocation Of Equity To Non Controlling Interests Stock issued during period, value, allocation of equity to non-controlling interests. Award Timing Predetermined Award Timing Predetermined [Flag] Advertising Agency Holding Company One Advertising Agency Holding Company One [Member] Advertising Agency Holding Company One Customer relationships Customer Relationships [Member] Recently Issued and Recent Adopted Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Diluted (USD per share) Earnings Per Share, Diluted Class of Stock Class of Stock [Axis] Title and Position [Domain] Title and Position [Domain] Finite-Lived Intangible Assets by Major Class Finite-Lived Intangible Assets by Major Class [Axis] Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Summary of Amortization of Intangible Assets Recorded in Consolidated Statements of Operations Finite-Lived Intangible Assets Amortization Expense [Table Text Block] Noncash lease expense Operating Lease, Right-of-Use Asset, Periodic Reduction Name Measure Name Entity Interactive Data Current Entity Interactive Data Current Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] TRA liability Tax Receivable Agreement Liability Tax receivable agreement liability. Operating lease assets obtained in exchange for operating lease liabilities including adjustments Right-of-Use Asset Obtained in Exchange for Operating Lease Liability, Net Of Adjustments Right-of-Use Asset Obtained in Exchange for Operating Lease Liability, Net Of Adjustments Ownership Ownership [Axis] Preferred stock, shares issued (shares) Preferred Stock, Shares Issued Customer Customer [Axis] Disaggregation Of Revenue [Table] Disaggregation of Revenue [Table] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Stock-based compensation Share-Based Payment Arrangement, Noncash Expense Transfers to noncontrolling interests: Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Net [Abstract] Sales and marketing Selling and Marketing Expense Net income Net income Net loss Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Technology and development Technology And Development [Member] Technology and development. Provision for (benefit from) income taxes Income Tax Expense (Benefit) Accounts Receivable, Allowance for Credit Loss [Roll Forward] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Supplemental disclosure of cash flow information: Supplemental Cash Flow Information [Abstract] Unrecognized stock-based compensation expected to be recognized over a weighted-average period Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Revenue Revenue from Contract with Customer, Excluding Assessed Tax Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Total other expense (income), net Nonoperating Income (Expense) Document - Document and Entity Information [Abstract] Document Document And Entity Information [Abstract] Document Document And Entity Information [Abstract] Concentration Risk Benchmark Concentration Risk Benchmark [Domain] Tim Vanderhook [Member] Tim Vanderhook Effective tax rate Effective Income Tax Rate Reconciliation, Percent Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Income (loss) from operations Operating Income (Loss) Variable Rate Variable Rate [Domain] Non-Marketable Equity Securities Equity Method Investments [Policy Text Block] Total liabilities and stockholders’ equity Liabilities and Equity Subsequent Events Subsequent Events [Text Block] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] All Adjustments to Compensation All Adjustments to Compensation [Member] Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Additional paid-in capital Additional Paid in Capital Capitalized software development costs Capitalized Software Development Costs [Member] Capitalized software development costs. Minority Interest [Table] Noncontrolling Interest [Table] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Legal Entity Legal Entity [Axis] Interest income, net Interest Income (Expense), Nonoperating Finite-Lived Intangible Assets, Major Class Name Finite-Lived Intangible Assets, Major Class Name [Domain] Repurchase of stock related to the stock repurchase program Payment, Tax Withholding, Share-Based Payment Arrangement, Share Repurchase Program Payment, Tax Withholding, Share-Based Payment Arrangement, Share Repurchase Program Customer One Customer One [Member] Customer One Underlying Security Market Price Change Underlying Security Market Price Change, Percent Individual: Individual [Axis] Canceled (USD per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Expected term (in years) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term Entity Address, State or Province Entity Address, State or Province Viant Technology LLC Viant Technology L L C [Member] Viant Technology LLC. Property Plant And Equipment [Line Items] Property, Plant and Equipment [Line Items] Statement [Line Items] Statement [Line Items] Decrease in the additional-paid-in-capital of Viant Technology Inc. resulting from ownership changes in Viant Technology LLC Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Ownership Changes Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Ownership Changes Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Contractual obligation, to be paid 2025 Contractual Obligation, to be Paid, Year Two Schedule of Major Classes of Property, Equipment and Software Property, Plant and Equipment [Table Text Block] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Thereafter Finite-Lived Intangible Asset, Expected Amortization, After Year Four Finite-Lived Intangible Asset, Expected Amortization, After Year Four Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Weighted-Average Grant-Date Fair Value of RSUs outstanding, beginning balance (USD per share) Weighted-Average Grant-Date Fair Value of RSUs outstanding, ending balance (USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Liabilities and stockholders’ equity Liabilities and Equity [Abstract] Vested and exercisable (USD per share) Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Exercisable Weighted Average Exercise Price Share based compensation arrangement by share based payment award options vested and exercisable weighted average exercise price. Minimum Minimum [Member] Restatement Determination Date Restatement Determination Date Payment of offering costs Payments for Repurchase of Initial Public Offering Adoption Date Trading Arrangement Adoption Date Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Schedule Of Property Plant And Equipment [Table] Property, Plant and Equipment [Table] Weighted-Average Exercise Price of outstanding, beginning balance (USD per share) Weighted-Average Exercise Price of outstanding, ending balance (USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price Operating lease assets, net Operating Lease, Right-of-Use Asset Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Number of Options outstanding, beginning balance (shares) Number of Options outstanding, ending balance (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Remaining lease term, short-term leases Lessee, Operating Lease, Remaining Lease Term, Short-Term Leases Lessee, Operating Lease, Remaining Lease Term, Short-Term Leases Provision for doubtful accounts Accounts Receivable, Credit Loss Expense (Reversal) Segments [Axis] Segments [Axis] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Exchange units for shares of common stock (shares) Exchange Units For Shares Of Common Stock Exchange units for shares of common stock. U.S. statutory federal income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Contractual obligations, remainder of 2023 Contractual Obligation, to be Paid, Remainder of Fiscal Year Exercise Price Award Exercise Price Chris Vanderhook [Member] Chris Vanderhook Loss Per Share Earnings Per Share [Text Block] Arrangement Duration Trading Arrangement Duration Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Operating expenses: Costs and Expenses [Abstract] Less: Imputed interest Lessee Operating Lease Liability Imputed Interest Lessee operating lease liability imputed interest. Stockholders’ equity Equity, Attributable to Parent [Abstract] Granted (USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted-Average Remaining Contractual Term of Options, Vested and exercisable Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Exercisable Weighted Average Remaining Contractual Term Share based compensation arrangement by share based payment award options vested and exercisable weighted average remaining contractual term. Share repurchase program, additional authorized, amount Share Repurchase Program, Additional Authorized, Amount Share Repurchase Program, Additional Authorized, Amount Units Owned (shares) Number Of Units Owned Number of units owned. Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Expected Duration of Greater Than One Year Long-Term Contract with Customer [Member] Segments [Domain] Segments [Domain] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] 2029 Finite-Lived Intangible Asset, Expected Amortization, Year Four All Individuals All Individuals [Member] Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation and Significant Accounting Policies [Text Block] Trademarks/tradenames Trademarks and Trade Names [Member] Vested and exercisable (shares) Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Exercisable Number Of Shares Share based compensation arrangement by share based payment award options vested and exercisable number of shares. PEO PEO [Member] Variable Rate Variable Rate [Axis] Contract with Customer, Duration Contract with Customer, Duration [Domain] Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Name Trading Arrangement, Individual Name Other expense, net Other Nonoperating Income (Expense) Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Change from net income attributable to Viant Technology Inc. and transfers to noncontrolling interests Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Change Due to Net Income Attributable to Parent and Effects of Changes, Net Long-Lived Tangible Asset Long-Lived Tangible Asset [Axis] Operating leases for office space remaining lease terms Lessee, Operating Lease, Remaining Lease Term Schedule of Depreciation Schedule Of Depreciation Expense Table [Table Text Block] Schedule of depreciation expense. Capitalized software development costs Payments to Develop Software Facility fee for undrawn amounts Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Schedule of Concentration of Credit Risk Schedules of Concentration of Risk, by Risk Factor [Table Text Block] Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Lender Name Lender Name [Axis] Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table] Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Related Party [Domain] Related and Nonrelated Parties [Domain] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Members Equity Class B Units Members Equity Class B Units [Member] Members Equity Class B Units Local Phone Number Local Phone Number Supplier Supplier [Axis] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Expected volatility Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Summary of RSU Activity Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Repurchase of stock related to the stock repurchase program (shares) Stock Repurchased During Period, Shares Exchange of Class B common stock for Class A common stock (shares) Stock Issued During Period, Shares, Conversion of Units Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] PEO Total Compensation Amount PEO Total Compensation Amount Long-Lived Tangible Asset Long-Lived Tangible Asset [Domain] Summary of Accrued Liabilities Schedule of Accrued Liabilities [Table Text Block] Income Statement Location Statement of Income Location, Balance [Axis] Entity Ex Transition Period Entity Ex Transition Period Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Reissuance of treasury stock Stock Issued During Period, Value, Treasury Stock Reissued Common Stock Common Stock [Member] Measure: Measure [Axis] Basis of Presentation and Principles of Consolidation Basis Of Presentation And Principles Of Consolidation Policy [Policy Text Block] Basis of presentation and principles of consolidation. Contractual obligation, to be paid 2026 Contractual Obligation, to be Paid, Year Three Preferred stock, shares authorized (shares) Preferred Stock, Shares Authorized Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Entity Emerging Growth Company Entity Emerging Growth Company Entity Central Index Key Entity Central Index Key General and administrative General and Administrative Expense [Member] Lessee Lease Description [Table] Lessee, Lease, Description [Table] Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Equity Component Equity Component [Domain] Preferred stock, par value (USD per share) Preferred Stock, Par or Stated Value Per Share Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Accrued member tax distributions Adjustments To Additional Paid In Capital Accrued Member Tax Distributions Adjustments to additional paid in capital, accrued member tax distributions. Stock-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Entity Shell Company Entity Shell Company Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Comprehensive Income (Loss) Comprehensive Income, Policy [Policy Text Block] Class B Common Stock Common Class B [Member] Title Trading Arrangement, Individual Title Statement [Table] Statement [Table] Consolidation Items [Domain] Consolidation Items [Domain] City Area Code City Area Code Current liabilities: Liabilities, Current [Abstract] Reissuance of treasury stock in connection with equity-based compensation plans (shares) Stock Issued During Period, Shares, Treasury Stock Reissued Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Concentration Risk Benchmark Concentration Risk Benchmark [Axis] Loss on disposal of assets Gain (Loss) on Disposition of Assets Total current assets Assets, Current Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Other platform operations Other Platform Operations [Member] Other Platform Operations Accrued liabilities Increase (Decrease) in Accrued Liabilities Document Information [Line Items] Document Information [Line Items] Long-term debt Long-Term Debt, Excluding Current Maturities Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Income Taxes and Tax Receivable Agreement Income Tax Disclosure [Text Block] 2029 Lessee, Operating Lease, Liability, to be Paid, Year Four Earnings (loss) per share of Class A common stock: Earnings Per Share [Abstract] Accumulated deficit Retained Earnings (Accumulated Deficit) Class of Stock Class of Stock [Domain] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Retirement of treasury stock (in shares) Treasury Stock, Shares, Retired General and administrative General and Administrative Expense Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Equity Awards Adjustments Equity Awards Adjustments [Member] Present value of operating lease liabilities Operating Lease, Liability Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Underlying Securities Award Underlying Securities Amount Credit Facility Credit Facility [Axis] Schedule of Traffic Acquisition Costs Deferred Policy Acquisition Costs [Table Text Block] Amendment Flag Amendment Flag Provision for doubtful accounts Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease) Entity Registrant Name Entity Registrant Name Point-in-time revenue Transferred at Point in Time [Member] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Depreciation and amortization Depreciation, Depletion and Amortization Timing of Transfer of Good or Service Timing of Transfer of Good or Service [Axis] Traffic acquisition costs Traffic Acquisition [Member] Traffic Acquisition Intangible Assets, Net Intangible Assets Disclosure [Text Block] Fair Value as of Grant Date Award Grant Date Fair Value Anti-dilutive shares excluded from loss per share of Class A common stock—diluted: Antidilutive Securities Excluded From Earnings Loss Per Share [Abstract] Antidilutive securities excluded from earnings (loss) per share. Customer Concentration Risk Customer Concentration Risk [Member] Basis Of Presentation And Summary Of Significant Accounting Policies [Table] Basis Of Presentation And Summary Of Significant Accounting Policies [Table] Basis of presentation and summary of significant accounting policies. Subsequent Events [Abstract] Affiliated Entity Affiliated Entity [Member] Revolving Credit Facility Debt Disclosure [Text Block] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Summary of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Net income attributable to Viant Technology, Inc.—diluted Net Income (Loss) Attributable to Parent, Diluted Cumulative days available for use (less than) Short-Term Lease, Cumulative Days Available For Use Short-Term Lease, Cumulative Days Available For Use Entity Address, Postal Zip Code Entity Address, Postal Zip Code Summary of Stock-based Compensation Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Restatement Determination Date: Restatement Determination Date [Axis] Title of 12(b) Security Title of 12(b) Security Concentration Risk Type Concentration Risk Type [Axis] Common stock Common Stock, Value, Issued Share-Based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Individual Customer B Individual Customer B [Member] Individual Customer B Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Aggregate Intrinsic Value, Vested and exercisable Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Finite Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Canceled/forfeited (USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Preferred stock, $0.001 par value Preferred Stock, Value, Issued Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward] Accrued liabilities Accrued Liabilities Noncontrolling Interests Noncontrolling Interest Disclosure [Text Block] Basic (USD per share) Earnings Per Share, Basic Nonqualified Stock Options Nonqualified Stock Options Nonqualified Stock Options [Member] Nonqualified stock options. Accounts payable Increase (Decrease) in Accounts Payable Cash paid for amounts included in operating lease liabilities Operating Lease, Payments Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Share-based compensation arrangement by share-based payment award, contractual term Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period Furniture, fixtures and office equipment Furniture Fixtures And Office Equipment [Member] Furniture, fixtures and office equipment. Ownership Ownership [Domain] Contractual obligation, to be paid 2024 Contractual Obligation, to be Paid, Year One Capitalized assets financed by accounts payable and accrued liabilities Capital Expenditures Incurred but Not yet Paid Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Net loss attributable to Viant Technology Inc. Net Income (Loss) Available to Common Stockholders, Basic Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Basis Of Presentation And Summary Of Significant Accounting Policies [Abstract] Basis Of Presentation And Summary Of Significant Accounting Policies [Abstract] Basis of Presentation and Summary of Significant Accounting Policies. Total current liabilities Liabilities, Current Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Weighted-average shares of Class A common stock outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] TRA, unrecorded liability Tax Receivable Agreement, Unrecorded Liability Tax Receivable Agreement, Unrecorded Liability Total assets Assets Concentration of Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] 2026 Finite-Lived Intangible Asset, Expected Amortization, Year One Platform operations Cost of Goods and Services Sold Outstanding balance Long-Term Line of Credit Share based payment award equity instruments other than options grants in period Granted (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Commitments and contingencies (Note 13) Commitments and Contingencies Termination Date Trading Arrangement Termination Date Nature of Operations Nature of Operations [Text Block] Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Table] 2027 Lessee, Operating Lease, Liability, to be Paid, Year Two Supplier Two Supplier Two [Member] Supplier Two Stock-Based Compensation Share-Based Payment Arrangement [Text Block] Undrawn availability percentage Line Of Credit Facility, Undrawn Availability Percentage Line Of Credit Facility, Undrawn Availability Percentage Entity Address, City or Town Entity Address, City or Town Debt Instrument Debt Instrument [Axis] Summary of Nonqualified Stock Option Activity Share-Based Payment Arrangement, Option, Activity [Table Text Block] Noncontrolling Interest [Abstract] Noncontrolling Interest [Abstract] Ownership percentage by non-controlling interests Economic Interests Ownership Percentage Economic interests ownership percentage. Stock-based compensation expense Share-Based Payment Arrangement, Expense Net income attributable to Viant Technology Inc. Net income attributable to Viant Technology Inc. Net Income (Loss) Attributable to Parent Trading Arrangement: Trading Arrangement [Axis] Platform operations Platform Operations [Member] Platform operations. Granted (USD per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Canceled/forfeited (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Summary of Balances of Intangible Assets and Accumulated Amortization Schedule of Finite-Lived Intangible Assets [Table Text Block] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] PNC Bank P N C Bank [Member] PNC Bank. Entity File Number Entity File Number Revenue Revenue from Contract with Customer [Text Block] Document Fiscal Year Focus Document Fiscal Year Focus Noncontrolling Interests Noncontrolling Interest [Member] Income Statement [Abstract] Income Statement [Abstract] Entity Address, Address Line One Entity Address, Address Line One Repurchase of stock related to tax withholdings on vested equity awards Treasury Stock, Value, Acquired, Cost Method Entity Address, Address Line Two Entity Address, Address Line Two Debt Instrument, Name Debt Instrument, Name [Domain] Other accrued liabilities Other Accrued Liabilities, Current Name Forgone Recovery, Individual Name Remainder of 2025 Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year Operating lease weighted average remaining lease term Operating Lease, Weighted Average Remaining Lease Term Add back: Reallocation of net income attributable to noncontrolling interest from the assumed exchange of RSUs and NQSOs for Class A common stock Dilutive Securities, Effect on Basic Earnings Per Share, ESOP Convertible Preferred Stock, Net Dilutive Securities, Effect on Basic Earnings Per Share, ESOP Convertible Preferred Stock, Net Document Period End Date Document Period End Date Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Accrued traffic acquisition costs Accrued Traffic Acquisition Costs Accrued traffic acquisition costs. Total undiscounted future lease payments Lessee, Operating Lease, Liability, to be Paid RSUs outstanding, beginning balance (shares) RSUs outstanding, ending balance (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Deferred revenue Increase (Decrease) in Deferred Revenue Expired (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Expirations in Period Line of Credit Facility, Lender Line of Credit Facility, Lender [Domain] Insider Trading Arrangements [Line Items] Line Of Credit Facility [Line Items] Line of Credit Facility [Line Items] Payment of member tax distributions Payment Of Member Tax Distributions Payment of member tax distributions. Timing of Transfer of Good or Service Timing of Transfer of Good or Service [Domain] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Income tax benefit (expense) from the assumed exchange of dilutive securities for Class A common stock Dilutive Securities, Effect on Basic Earnings Per Share, ESOP Convertible Preferred Stock, Income Tax Effect Dilutive Securities, Effect on Basic Earnings Per Share, ESOP Convertible Preferred Stock, Income Tax Effect Retirement of treasury stock Treasury Stock, Retired, Cost Method, Amount 2028 Lessee, Operating Lease, Liability, to be Paid, Year Three PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Adjustment to Compensation: Adjustment to Compensation [Axis] Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Accounts Receivable Accounts Receivable [Member] Less: Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Document Transition Report Document Transition Report Document Quarterly Report Document Quarterly Report Customer Customer [Domain] Entity Current Reporting Status Entity Current Reporting Status Accumulated Deficit Retained Earnings [Member] Ownership percentage by Viant Technology Inc. Subsidiary, Ownership Percentage, Noncontrolling Owner Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] JOBS Act Election as an Emerging Growth Company J O B S Act Election As Emerging Growth Company Policy Policy [Policy Text Block] JOBS Act Election as an Emerging Growth Company Policy. Related Party [Axis] Related and Nonrelated Parties [Axis] Basic (shares) Weighted-average shares of Class A common stock outstanding—basic (shares) Weighted Average Number of Shares Outstanding, Basic Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Document Information [Table] Document Information [Table] Total equity Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Units Owned, Noncontrolling Interest (shares) Number Of Units Owned, Noncontrolling Interest Number of units owned. Restricted Stock Units Restricted Stock Units (RSUs) [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Executive Category: Executive Category [Axis] Cash paid for investments Payments to Acquire Investments Name Awards Close in Time to MNPI Disclosures, Individual Name Contract with Customer, Duration Contract with Customer, Duration [Axis] Canceled (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period Entity Filer Category Entity Filer Category Beginning balance (shares) Ending balance (shares) Shares, Issued Revenue for unsatisfied performance obligation expected to be recognized in the future, amount Revenue, Remaining Performance Obligation, Amount Income Statement Location Statement of Income Location, Balance [Domain] Company Selected Measure Name Company Selected Measure Name