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Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Preferred stock, shares outstanding (shares) Preferred Stock, Shares Outstanding Percentage of voting rights of outstanding common stock Percentage Of Voting Rights Of Outstanding Common Stock Percentage of voting rights of outstanding common stock. Debt Instrument Debt Instrument [Axis] Total property, equipment and software Property, Plant and Equipment, Gross Member units acquired (shares) Members Equity Units Acquired During Period Member units acquired during period shares. Senior secured revolving credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Expenses incurred Related Party Transaction, Expenses from Transactions with Related Party Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Fixed coverage charge ratio Line Of Credit Facility, Fixed Coverage Charge Ratio Line Of Credit Facility, Fixed Coverage Charge Ratio Purchased software Software and Software Development Costs [Member] Accrued compensation Increase Decrease In Accrued Compensation Increase decrease in Accrued compensation. Additional paid-in capital Additional Paid in Capital Debt instrument, basis spread on variable rate plus margin Debt Instrument, Basis Spread on Variable Rate Statistical Measurement Statistical Measurement [Domain] Continuing Members Class B Units Continuing Members Class B Units [Member] Continuing members class B units. Depreciation Depreciation Share-Based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Abstract] 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. Repurchase of treasury stock in connection with the taxes paid related to net share settlement of equity awards Treasury Stock, Value, Acquired, Cost Method Net loss attributable to Viant Technology Inc. Net loss attributable to Viant Technology Inc. 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Operating expenses: Costs and Expenses [Abstract] Lender Name Lender Name [Axis] Canceled (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period Transfers to noncontrolling interests: Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Net [Abstract] Legal Entity Legal Entity [Axis] Long-term debt Long-Term Debt, Excluding Current Maturities Total liabilities Liabilities Technology and development Technology And Development Expenses Technology and development expenses. Operating lease weighted average remaining lease term Operating Lease, Weighted Average Remaining Lease Term Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Supplier One Supplier One [Member] Supplier one. Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Revolving Credit Facility Revolving Credit Facility [Member] Schedule of Major Classes of Property, Equipment and Software Property, Plant and Equipment [Table Text Block] Summary Ownership of Viant Technology LLC Schedule Of Noncontrolling Ownership Interests Table [Table Text Block] Schedule of noncontrolling ownership interests. 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Total assets Assets Write-offs, net of recoveries Accounts Receivable, Allowance for Credit Loss, Writeoff Debt Disclosure [Abstract] Debt Disclosure [Abstract] Supplier Supplier [Domain] Loss per share of Class A common stock: Earnings Per Share [Abstract] Accounts Receivable, Net of Allowances Accounts Receivable [Policy Text Block] Income Statement Location Income Statement Location [Axis] Antidilutive Securities Antidilutive Securities [Axis] Accrued liabilities Total accrued liabilities Accrued Liabilities, Current Contractual obligation, to be paid 2024 Contractual Obligation, to be Paid, Year One Numerator Net Income (Loss) Available to Common Stockholders, Basic [Abstract] Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Variable lease cost Variable Lease, Cost Stockholders’ equity Stockholders' Equity Attributable to Parent [Abstract] Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Cumulative Effect, Period of Adoption [Domain] Cumulative Effect, Period of Adoption [Domain] Noncontrolling Interests Noncontrolling Interest Disclosure [Text Block] Loss Per Share Earnings Per Share [Text Block] Customer Customer [Axis] 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] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Operating lease liabilities Increase (Decrease) in Operating Lease Liability Award Type Award Type [Domain] 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 Summary of Balances of Intangible Assets and Accumulated Amortization Schedule of Finite-Lived Intangible Assets [Table Text Block] Computer equipment Computer Equipment [Member] Entity Registrant Name Entity Registrant Name Common stock shares issued and sold (shares) Stock Issued During Period, Shares, New Issues Supplier Concentration Risk Supplier Concentration Risk [Member] Expected dividend yield assumption Expected dividend yield Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Customer relationships Customer Relationships [Member] Entity Address, City or Town Entity Address, City or Town Leases [Abstract] Leases [Abstract] Total equity Beginning balance Ending balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Minimum Minimum [Member] Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Entity Emerging Growth Company Entity Emerging Growth Company Customer Two Customer Two [Member] Customer Two Common stock, par value (USD per share) Common Stock, Par or Stated Value Per Share Viant Technology Inc. Viant Technology Inc [Member] Viant Technology Inc. Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Treasury Stock Treasury Stock, Common [Member] Trading Symbol Trading Symbol Entity File Number Entity File Number Intangible Assets, Net Intangible Assets Disclosure [Text Block] Treasury stock, shares (shares) Beginning balance, treasury stock (shares) Ending balance, treasury stock (shares) Treasury Stock, Common, Shares 2027 Finite-Lived Intangible Asset, Expected Amortization, Year Four Members equity units received in exchange of units (shares) Members Equity Units Received During Period Conversion Of Units Members equity units received during period conversion of units. 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Credit Facility Credit Facility [Domain] Amortization of intangible assets Amortization of Intangible Assets Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Basic (USD per share) Earnings Per Share, Basic 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. 2026 Lessee, Operating Lease, Liability, to be Paid, Year Three Advertising Agency Holding Company One Advertising Agency Holding Company One [Member] Advertising Agency Holding Company One Concentration Risk Type Concentration Risk Type [Domain] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Sales and marketing Selling and Marketing Expense Total stockholders’ equity attributable to Viant Technology Inc. Stockholders' Equity Attributable to Parent 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 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 TRA liability Tax Receivable Agreement Liability Tax receivable agreement liability. 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Class of Stock Class of Stock [Axis] Statement [Table] Statement [Table] 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] 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 Lessee operating lease renewal term Lessee, Operating Lease, Renewal Term Document Quarterly Report Document Quarterly Report Current assets: Assets, Current [Abstract] Long-term portion of operating lease liabilities Operating Lease, Liability, Noncurrent 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 Statistical Measurement Statistical Measurement [Axis] Document - Document and Entity Information [Abstract] Document Document And Entity Information [Abstract] Document Document And Entity Information [Abstract] Repurchase of treasury shares in connection with the taxes paid related to net share settlement of equity awards (shares) Treasury Stock, Shares, Acquired Line of Credit Facility, Lender Line of Credit Facility, Lender [Domain] Leasehold improvements Leasehold Improvements [Member] Accumulated deficit Retained Earnings (Accumulated Deficit) Accounts receivable, net of allowances Accounts Receivable, after Allowance for Credit Loss, Current Schedule Of Finite Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Equity Components Equity Components [Axis] Timing of Transfer of Good or Service Timing of Transfer of Good or Service [Axis] Comprehensive Loss Comprehensive Income, Policy [Policy Text Block] Expired (USD per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price Capitalized software development costs Capitalized Software Development Costs [Member] Capitalized software development costs. Interest expense (income), net Interest Income (Expense), Nonoperating, Net Document Fiscal Year Focus Document Fiscal Year Focus Summary of Amortization of Intangible Assets Recorded in Consolidated Statements of Operations Finite-Lived Intangible Assets Amortization Expense [Table Text Block] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Statement [Line Items] Statement [Line Items] 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 Total other expense (income), net Nonoperating Income (Expense) Variable Rate Variable Rate [Domain] Customer One Customer One [Member] Customer One Payments to acquire units Payments To Acquire Member Units Payments to acquire member units. Gross Amount Finite-Lived Intangible Assets, Gross Operating lease assets Operating Lease, Right-of-Use Asset Viant Technology LLC Viant Technology L L C [Member] Viant Technology LLC. 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 Document Transition Report Document Transition Report Local Phone Number Local Phone Number Summary of Nonqualified Stock Option Activity Share-Based Payment Arrangement, Option, Activity [Table Text Block] Loss from operations Operating Income (Loss) Contractual obligation, to be paid 2025 Contractual Obligation, to be Paid, Year Two Recent Adopted Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Thereafter Finite-Lived Intangible Asset, Expected Amortization, After Year Four Finite-Lived Intangible Asset, Expected Amortization, After Year Four Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Document Information [Table] Document Information [Table] Common stock, shares outstanding (shares) Common Stock, Shares, Outstanding Goodwill Goodwill 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. 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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 Contractual obligations, remainder of 2023 Contractual Obligation, to be Paid, Remainder of Fiscal Year Short-term lease cost Short-Term Lease, Cost Preferred stock, shares authorized (shares) Preferred Stock, Shares Authorized 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. Contractual obligation, to be paid 2026 Contractual Obligation, to be Paid, Year Three Less: Net loss attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Current liabilities: Liabilities, Current [Abstract] Net loss attributable to Viant Technology Inc. Net Income (Loss) Available to Common Stockholders, Basic Common stock, shares issued (shares) Common Stock, Shares, Issued Current portion of deferred revenue Contract with Customer, Liability, Current Capitalized assets financed by accounts payable and accrued liabilities Capital Expenditures Incurred but Not yet Paid Income Statement Location Income Statement Location [Domain] Over-time revenue Transferred over Time [Member] Schedule of Depreciation Schedule Of Depreciation Expense Table [Table Text Block] Schedule of depreciation expense. Amendment Flag Amendment Flag Operating leases for office space remaining lease terms Lessee, Operating Lease, Remaining Lease Term Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Operating lease cost Operating Lease, Cost Entity Current Reporting Status Entity Current Reporting Status Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Other current liabilities Other Liabilities, Current Other assets Other Assets, Noncurrent Nature Of Operations [Line Items] Nature Of Operations [Line Items] Nature of Operations. Depreciation and amortization Depreciation, Depletion and Amortization Disaggregation Of Revenue [Table] Disaggregation of Revenue [Table] Facility fee for undrawn amounts Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Contract with Customer, Duration Contract with Customer, Duration [Axis] U.S. statutory federal income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Reissuance of treasury stock in connection with equity-based compensation plans Stock Issued During Period, Value, Treasury Stock Reissued Expected Duration of Greater Than One Year Long-Term Contract with Customer [Member] 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 Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code 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] Liabilities Liabilities [Abstract] Property, equipment, and software, net Total property, equipment and software, net Property, Plant and Equipment, Net Cash paid for amounts included in operating lease liabilities Operating Lease, Payments Summary of Estimated Future Amortization of Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] 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. 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Intangible assets, net Net Carrying Amount Finite-Lived Intangible Assets, Net Line Of Credit Facility [Table] Line of Credit Facility [Table] Unrecognized stock-based compensation expected to be recognized Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount 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] Property, Equipment and Software, Net Property, Plant and Equipment Disclosure [Text Block] Issuance of Class A common stock in connection with equity-based compensation plans (shares) Stock Issued During Period, Shares, Employee Benefit Plan Change from net loss 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 Aggregate Intrinsic Value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value Long-Lived Tangible Asset Long-Lived Tangible Asset [Domain] Accounts receivable Increase (Decrease) in Accounts Receivable Title of 12(b) Security Title of 12(b) Security Ownership percentage by Viant Technology Inc. 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Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] Nonqualified Stock Options Nonqualified Stock Options Nonqualified Stock Options [Member] Nonqualified stock options. Current Fiscal Year End Date Current Fiscal Year End Date Accrued Liabilities Accounts Payable and Accrued Liabilities Disclosure [Text Block] Furniture, fixtures and office equipment Furniture Fixtures And Office Equipment [Member] Furniture, fixtures and office equipment. Finite Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Diluted (USD per share) Earnings Per Share, Diluted Sale of Stock Sale of Stock [Domain] Trademarks/tradenames Trademarks and Trade Names [Member] Payments of stock issuance costs Payments of Stock Issuance Costs Stock-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Concentration Risk Type Concentration Risk Type [Axis] Total current liabilities Liabilities, Current 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. 2025 Lessee, Operating Lease, Liability, to be Paid, Year Two Customer Concentration Risk Customer Concentration Risk [Member] Summary of RSU Activity Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Entity Ex Transition Period Entity Ex Transition Period Underwrites options exercised shares issued (shares) Stock Issued During Period Shares Underwrites Options Exercised Stock issued during period shares underwrites options exercised. Capitalized software development costs Payments to Develop Software Revenue for unsatisfied performance obligation expected to be recognized in the future, amount Revenue, Remaining Performance Obligation, Amount Cumulative Effect, Period of Adoption, Adjustment Cumulative Effect, Period of Adoption, Adjustment [Member] Summary of Changes in Allowance for Doubtful Accounts Accounts Receivable, Allowance for Credit Loss [Table Text Block] Summary of Future Minimum Lease Payments Lessee, Operating Lease, Liability, Maturity [Table Text Block] Entity Address, Address Line Two Entity Address, Address Line Two Entity Address, Address Line One Entity Address, Address Line One Supplier Two Supplier Two [Member] Supplier Two Undrawn availability percentage Line Of Credit Facility, Undrawn Availability Percentage Line Of Credit Facility, Undrawn Availability Percentage Stock-based compensation included in capitalized software development costs Share-Based Payment Arrangement, Amount Capitalized Underwriters Over-Allotment Option [Member] Class of Stock Class of Stock [Domain] Interest cost incurred Interest Expense Ownership percentage by non-controlling interests Economic Interests Ownership Percentage Economic interests ownership percentage. Credit Facility Credit Facility [Axis] Platform operations Platform Operations [Member] Platform operations. Summary of Accrued Liabilities Schedule of Accrued Liabilities [Table Text Block] Vested (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Entity Tax Identification Number Entity Tax Identification Number PNC Bank P N C Bank [Member] PNC Bank. Summary of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Common stock voting rights percentage Common Stock Voting Rights Percentage Common stock voting rights percentage. Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Remainder of 2023 Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year Accrued traffic acquisition costs Accrued Traffic Acquisition Costs Accrued traffic acquisition costs. Net decrease in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Issuance of Class A common stock in connection with equity-based compensation plans Stock Issued During Period, Value, Employee Benefit Plan Payment of member tax distributions Payment Of Member Tax Distributions Payment of member tax distributions. Entity Central Index Key Entity Central Index Key Antidilutive Securities, Name Antidilutive Securities, Name [Domain] 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] Finite-Lived Intangible Assets by Major Class Finite-Lived Intangible Assets by Major Class [Axis] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Exchange of Class B common stock for Class A common stock (shares) Stock Issued During Period, Shares, Conversion of Units Concentration of Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Other accrued liabilities Other Accrued Liabilities, Current Entity Entity [Domain] City Area Code City Area Code Assets Assets [Abstract] General and administrative General and Administrative Expense Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Sale of Stock Sale of Stock [Axis] Payable to related parties Due to Related Parties, Current Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] 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. Supplemental disclosure of non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Stock-based compensation Share-Based Payment Arrangement, Noncash Expense Weighted-average grant-date fair value of stock options granted (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Variable Rate Variable Rate [Axis] Other liabilities Increase (Decrease) in Other Operating Liabilities Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Disaggregation Of Revenue [Line Items] Disaggregation of Revenue [Line Items] 2024 Finite-Lived Intangible Asset, Expected Amortization, Year One Calculation of Basic and Diluted Net Loss Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Operating lease assets obtained in exchange for operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Customer Customer [Domain]