3.21.2 html 568 622 1 true 133 0 false 11 false false R1.htm 000100 - Document - Document and Entity Information Sheet http://billtrust.com/role/DocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 010000 - Statement - Balance Sheets (FY) Sheet http://billtrust.com/role/BalanceSheetsFy Balance Sheets (FY) Statements 2 false false R3.htm 010100 - Statement - Balance Sheets (FY) (Parenthetical) Sheet http://billtrust.com/role/BalanceSheetsFyParenthetical Balance Sheets (FY) (Parenthetical) Statements 3 false false R4.htm 020000 - Statement - Statements of Operations and Comprehensive Loss (FY) Sheet http://billtrust.com/role/StatementsOfOperationsAndComprehensiveLossFy Statements of Operations and Comprehensive Loss (FY) Statements 4 false false R5.htm 030000 - Statement - Statements of Stockholders' Equity (FY) Sheet http://billtrust.com/role/StatementsOfStockholdersEquityFy Statements of Stockholders' Equity (FY) Statements 5 false false R6.htm 040000 - Statement - Statements of Cash Flows (FY) Sheet http://billtrust.com/role/StatementsOfCashFlowsFy Statements of Cash Flows (FY) Statements 6 false false R7.htm 050000 - Statement - Condensed Consolidated Balance Sheets (Q1) Sheet http://billtrust.com/role/CondensedConsolidatedBalanceSheetsQ1 Condensed Consolidated Balance Sheets (Q1) Statements 7 false false R8.htm 050100 - Statement - Condensed Consolidated Balance Sheets (Q1) (Parenthetical) Sheet http://billtrust.com/role/CondensedConsolidatedBalanceSheetsQ1Parenthetical Condensed Consolidated Balance Sheets (Q1) (Parenthetical) Statements 8 false false R9.htm 060000 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) (Q1) Sheet http://billtrust.com/role/CondensedConsolidatedStatementsOfOperationsAndComprehensiveLossUnauditedQ1 Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) (Q1) Statements 9 false false R10.htm 070000 - Statement - Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Deficit (Unaudited) (Q1) Sheet http://billtrust.com/role/CondensedConsolidatedStatementsOfRedeemableConvertiblePreferredStockAndStockholdersDeficitUnauditedQ1 Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Deficit (Unaudited) (Q1) Statements 10 false false R11.htm 080000 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited) (Q1) Sheet http://billtrust.com/role/CondensedConsolidatedStatementsOfCashFlowsUnauditedQ1 Condensed Consolidated Statements of Cash Flows (Unaudited) (Q1) Statements 11 false false R12.htm 090100 - Disclosure - Organization and Nature of Business (FY) Sheet http://billtrust.com/role/OrganizationAndNatureOfBusinessFy Organization and Nature of Business (FY) Notes 12 false false R13.htm 090200 - Disclosure - Significant Accounting Policies (FY) Sheet http://billtrust.com/role/SignificantAccountingPoliciesFy Significant Accounting Policies (FY) Notes 13 false false R14.htm 090300 - Disclosure - Acquisitions (FY) Sheet http://billtrust.com/role/AcquisitionsFy Acquisitions (FY) Notes 14 false false R15.htm 090400 - Disclosure - Revenue from Contracts with Customers (FY) Sheet http://billtrust.com/role/RevenueFromContractsWithCustomersFy Revenue from Contracts with Customers (FY) Notes 15 false false R16.htm 090500 - Disclosure - Fair Value Measurements (FY) Sheet http://billtrust.com/role/FairValueMeasurementsFy Fair Value Measurements (FY) Notes 16 false false R17.htm 090600 - Disclosure - Goodwill and Intangible Assets, net (FY) Sheet http://billtrust.com/role/GoodwillAndIntangibleAssetsNetFy Goodwill and Intangible Assets, net (FY) Notes 17 false false R18.htm 090700 - Disclosure - Property and Equipment, net (FY) Sheet http://billtrust.com/role/PropertyAndEquipmentNetFy Property and Equipment, net (FY) Notes 18 false false R19.htm 090800 - Disclosure - Current and Long-Term Debt and Capital Lease Obligations (FY) Sheet http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationsFy Current and Long-Term Debt and Capital Lease Obligations (FY) Notes 19 false false R20.htm 090900 - Disclosure - Incentive Compensation Plans (FY) Sheet http://billtrust.com/role/IncentiveCompensationPlansFy Incentive Compensation Plans (FY) Notes 20 false false R21.htm 091000 - Disclosure - Income Taxes (FY) Sheet http://billtrust.com/role/IncomeTaxesFy Income Taxes (FY) Notes 21 false false R22.htm 091100 - Disclosure - Commitments and Contingencies (FY) Sheet http://billtrust.com/role/CommitmentsAndContingenciesFy Commitments and Contingencies (FY) Notes 22 false false R23.htm 091200 - Disclosure - Segment Information (FY) Sheet http://billtrust.com/role/SegmentInformationFy Segment Information (FY) Notes 23 false false R24.htm 091300 - Disclosure - Related Party Transactions (FY) Sheet http://billtrust.com/role/RelatedPartyTransactionsFy Related Party Transactions (FY) Notes 24 false false R25.htm 091400 - Disclosure - Loss per Share (FY) Sheet http://billtrust.com/role/LossPerShareFy Loss per Share (FY) Notes 25 false false R26.htm 091500 - Disclosure - Subsequent Events (FY) Sheet http://billtrust.com/role/SubsequentEventsFy Subsequent Events (FY) Notes 26 false false R27.htm 091600 - Disclosure - Organization and Nature of Business (Q1) Sheet http://billtrust.com/role/OrganizationAndNatureOfBusinessQ1 Organization and Nature of Business (Q1) Notes 27 false false R28.htm 091700 - Disclosure - Summary of Significant Accounting Policies (Q1) Sheet http://billtrust.com/role/SummaryOfSignificantAccountingPoliciesQ1 Summary of Significant Accounting Policies (Q1) Notes 28 false false R29.htm 091800 - Disclosure - Contingent Consideration (Q1) Sheet http://billtrust.com/role/ContingentConsiderationQ1 Contingent Consideration (Q1) Notes 29 false false R30.htm 091900 - Disclosure - Business Combination (Q1) Sheet http://billtrust.com/role/BusinessCombinationQ1 Business Combination (Q1) Notes 30 false false R31.htm 092000 - Disclosure - Revenue from Contracts with Customers (Q1) Sheet http://billtrust.com/role/RevenueFromContractsWithCustomersQ1 Revenue from Contracts with Customers (Q1) Notes 31 false false R32.htm 092100 - Disclosure - Fair Value Measurements (Q1) Sheet http://billtrust.com/role/FairValueMeasurementsQ1 Fair Value Measurements (Q1) Notes 32 false false R33.htm 092200 - Disclosure - Goodwill and Intangible Assets, net (Q1) Sheet http://billtrust.com/role/GoodwillAndIntangibleAssetsNetQ1 Goodwill and Intangible Assets, net (Q1) Notes 33 false false R34.htm 092300 - Disclosure - Property and Equipment, net (Q1) Sheet http://billtrust.com/role/PropertyAndEquipmentNetQ1 Property and Equipment, net (Q1) Notes 34 false false R35.htm 092400 - Disclosure - Current and Long-Term Debt and Capital Lease Obligations (Q1) Sheet http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationsQ1 Current and Long-Term Debt and Capital Lease Obligations (Q1) Notes 35 false false R36.htm 092500 - Disclosure - Stockholders' Equity, Warrants and Redeemable Preferred Stock (Q1) Sheet http://billtrust.com/role/StockholdersEquityWarrantsAndRedeemablePreferredStockQ1 Stockholders' Equity, Warrants and Redeemable Preferred Stock (Q1) Notes 36 false false R37.htm 092600 - Disclosure - Incentive Compensation Plans (Q1) Sheet http://billtrust.com/role/IncentiveCompensationPlansQ1 Incentive Compensation Plans (Q1) Notes 37 false false R38.htm 092700 - Disclosure - Income Taxes (Q1) Sheet http://billtrust.com/role/IncomeTaxesQ1 Income Taxes (Q1) Notes 38 false false R39.htm 092800 - Disclosure - Commitments and Contingencies (Q1) Sheet http://billtrust.com/role/CommitmentsAndContingenciesQ1 Commitments and Contingencies (Q1) Notes 39 false false R40.htm 092900 - Disclosure - Segment Information (Q1) Sheet http://billtrust.com/role/SegmentInformationQ1 Segment Information (Q1) Notes 40 false false R41.htm 093000 - Disclosure - Related Party Transactions (Q1) Sheet http://billtrust.com/role/RelatedPartyTransactionsQ1 Related Party Transactions (Q1) Notes 41 false false R42.htm 093100 - Disclosure - Loss Per Share (Q1) Sheet http://billtrust.com/role/LossPerShareQ1 Loss Per Share (Q1) Notes 42 false false R43.htm 093200 - Disclosure - Accrued Expenses and Other (Q1) Sheet http://billtrust.com/role/AccruedExpensesAndOtherQ1 Accrued Expenses and Other (Q1) Notes 43 false false R44.htm 100200 - Disclosure - Significant Accounting Policies (FY) (Policies) Sheet http://billtrust.com/role/SignificantAccountingPoliciesFyPolicies Significant Accounting Policies (FY) (Policies) Policies http://billtrust.com/role/SignificantAccountingPoliciesFy 44 false false R45.htm 101700 - Disclosure - Summary of Significant Accounting Policies (Q1) (Policies) Sheet http://billtrust.com/role/SummaryOfSignificantAccountingPoliciesQ1Policies Summary of Significant Accounting Policies (Q1) (Policies) Policies http://billtrust.com/role/SignificantAccountingPoliciesFy 45 false false R46.htm 110200 - Disclosure - Significant Accounting Policies (FY) (Tables) Sheet http://billtrust.com/role/SignificantAccountingPoliciesFyTables Significant Accounting Policies (FY) (Tables) Tables http://billtrust.com/role/SignificantAccountingPoliciesFy 46 false false R47.htm 110300 - Disclosure - Acquisitions (FY) (Tables) Sheet http://billtrust.com/role/AcquisitionsFyTables Acquisitions (FY) (Tables) Tables http://billtrust.com/role/AcquisitionsFy 47 false false R48.htm 110500 - Disclosure - Fair Value Measurements (FY) (Tables) Sheet http://billtrust.com/role/FairValueMeasurementsFyTables Fair Value Measurements (FY) (Tables) Tables http://billtrust.com/role/FairValueMeasurementsFy 48 false false R49.htm 110600 - Disclosure - Goodwill and Intangible Assets, net (FY) (Tables) Sheet http://billtrust.com/role/GoodwillAndIntangibleAssetsNetFyTables Goodwill and Intangible Assets, net (FY) (Tables) Tables http://billtrust.com/role/GoodwillAndIntangibleAssetsNetFy 49 false false R50.htm 110700 - Disclosure - Property and Equipment, net (FY) (Tables) Sheet http://billtrust.com/role/PropertyAndEquipmentNetFyTables Property and Equipment, net (FY) (Tables) Tables http://billtrust.com/role/PropertyAndEquipmentNetFy 50 false false R51.htm 110800 - Disclosure - Current and Long-Term Debt and Capital Lease Obligations (FY) (Tables) Sheet http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationsFyTables Current and Long-Term Debt and Capital Lease Obligations (FY) (Tables) Tables http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationsFy 51 false false R52.htm 110900 - Disclosure - Incentive Compensation Plans (FY) (Tables) Sheet http://billtrust.com/role/IncentiveCompensationPlansFyTables Incentive Compensation Plans (FY) (Tables) Tables http://billtrust.com/role/IncentiveCompensationPlansFy 52 false false R53.htm 111000 - Disclosure - Income Taxes (FY) (Tables) Sheet http://billtrust.com/role/IncomeTaxesFyTables Income Taxes (FY) (Tables) Tables http://billtrust.com/role/IncomeTaxesFy 53 false false R54.htm 111100 - Disclosure - Commitments and Contingencies (FY) (Tables) Sheet http://billtrust.com/role/CommitmentsAndContingenciesFyTables Commitments and Contingencies (FY) (Tables) Tables http://billtrust.com/role/CommitmentsAndContingenciesFy 54 false false R55.htm 111200 - Disclosure - Segment Information (FY) (Tables) Sheet http://billtrust.com/role/SegmentInformationFyTables Segment Information (FY) (Tables) Tables http://billtrust.com/role/SegmentInformationFy 55 false false R56.htm 111400 - Disclosure - Loss per Share (FY) (Tables) Sheet http://billtrust.com/role/LossPerShareFyTables Loss per Share (FY) (Tables) Tables http://billtrust.com/role/LossPerShareFy 56 false false R57.htm 111700 - Disclosure - Summary of Significant Accounting Policies (Q1) (Tables) Sheet http://billtrust.com/role/SummaryOfSignificantAccountingPoliciesQ1Tables Summary of Significant Accounting Policies (Q1) (Tables) Tables http://billtrust.com/role/SummaryOfSignificantAccountingPoliciesQ1 57 false false R58.htm 111800 - Disclosure - Contingent Consideration (Q1) (Tables) Sheet http://billtrust.com/role/ContingentConsiderationQ1Tables Contingent Consideration (Q1) (Tables) Tables http://billtrust.com/role/ContingentConsiderationQ1 58 false false R59.htm 111900 - Disclosure - Business Combination (Q1) (Tables) Sheet http://billtrust.com/role/BusinessCombinationQ1Tables Business Combination (Q1) (Tables) Tables http://billtrust.com/role/BusinessCombinationQ1 59 false false R60.htm 112100 - Disclosure - Fair Value Measurements (Q1) (Tables) Sheet http://billtrust.com/role/FairValueMeasurementsQ1Tables Fair Value Measurements (Q1) (Tables) Tables http://billtrust.com/role/FairValueMeasurementsFy 60 false false R61.htm 112200 - Disclosure - Goodwill and Intangible Assets, net (Q1) (Tables) Sheet http://billtrust.com/role/GoodwillAndIntangibleAssetsNetQ1Tables Goodwill and Intangible Assets, net (Q1) (Tables) Tables http://billtrust.com/role/GoodwillAndIntangibleAssetsNetFy 61 false false R62.htm 112300 - Disclosure - Property and Equipment, net (Q1) (Tables) Sheet http://billtrust.com/role/PropertyAndEquipmentNetQ1Tables Property and Equipment, net (Q1) (Tables) Tables http://billtrust.com/role/PropertyAndEquipmentNetFy 62 false false R63.htm 112400 - Disclosure - Current and Long-Term Debt and Capital Lease Obligations (Q1) (Tables) Sheet http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationsQ1Tables Current and Long-Term Debt and Capital Lease Obligations (Q1) (Tables) Tables http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationsFy 63 false false R64.htm 112600 - Disclosure - Incentive Compensation Plans (Q1) (Tables) Sheet http://billtrust.com/role/IncentiveCompensationPlansQ1Tables Incentive Compensation Plans (Q1) (Tables) Tables http://billtrust.com/role/IncentiveCompensationPlansFy 64 false false R65.htm 112800 - Disclosure - Commitments and Contingencies (Q1) (Tables) Sheet http://billtrust.com/role/CommitmentsAndContingenciesQ1Tables Commitments and Contingencies (Q1) (Tables) Tables http://billtrust.com/role/CommitmentsAndContingenciesFy 65 false false R66.htm 112900 - Disclosure - Segment Information (Q1) (Tables) Sheet http://billtrust.com/role/SegmentInformationQ1Tables Segment Information (Q1) (Tables) Tables http://billtrust.com/role/SegmentInformationFy 66 false false R67.htm 113100 - Disclosure - Loss Per Share (Q1) (Tables) Sheet http://billtrust.com/role/LossPerShareQ1Tables Loss Per Share (Q1) (Tables) Tables http://billtrust.com/role/LossPerShareQ1 67 false false R68.htm 113200 - Disclosure - Accrued Expenses and Other (Q1) (Tables) Sheet http://billtrust.com/role/AccruedExpensesAndOtherQ1Tables Accrued Expenses and Other (Q1) (Tables) Tables http://billtrust.com/role/AccruedExpensesAndOtherQ1 68 false false R69.htm 120100 - Disclosure - Organization and Nature of Business (FY) (Details) Sheet http://billtrust.com/role/OrganizationAndNatureOfBusinessFyDetails Organization and Nature of Business (FY) (Details) Details http://billtrust.com/role/OrganizationAndNatureOfBusinessFy 69 false false R70.htm 120200 - Disclosure - Significant Accounting Policies, Liquidity (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesLiquidityFyDetails Significant Accounting Policies, Liquidity (FY) (Details) Details 70 false false R71.htm 120202 - Disclosure - Significant Accounting Policies, COVID-19 (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesCovid19FyDetails Significant Accounting Policies, COVID-19 (FY) (Details) Details 71 false false R72.htm 120204 - Disclosure - Significant Accounting Policies, Revenue Recognition (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesRevenueRecognitionFyDetails Significant Accounting Policies, Revenue Recognition (FY) (Details) Details 72 false false R73.htm 120206 - Disclosure - Significant Accounting Policies, Deferred Revenue (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesDeferredRevenueFyDetails Significant Accounting Policies, Deferred Revenue (FY) (Details) Details 73 false false R74.htm 120208 - Disclosure - Significant Accounting Policies, Deferred Commissions (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesDeferredCommissionsFyDetails Significant Accounting Policies, Deferred Commissions (FY) (Details) Details 74 false false R75.htm 120210 - Disclosure - Significant Accounting Policies, Warrants (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesWarrantsFyDetails Significant Accounting Policies, Warrants (FY) (Details) Details 75 false false R76.htm 120212 - Disclosure - Significant Accounting Policies, Deferred Implementation and Other Costs (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesDeferredImplementationAndOtherCostsFyDetails Significant Accounting Policies, Deferred Implementation and Other Costs (FY) (Details) Details 76 false false R77.htm 120214 - Disclosure - Significant Accounting Policies, Inventory (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesInventoryFyDetails Significant Accounting Policies, Inventory (FY) (Details) Details 77 false false R78.htm 120216 - Disclosure - Significant Accounting Policies, Property and Equipment, net, Inventory (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesPropertyAndEquipmentNetInventoryFyDetails Significant Accounting Policies, Property and Equipment, net, Inventory (FY) (Details) Details 78 false false R79.htm 120218 - Disclosure - Significant Accounting Policies, Capitalized Software Development Costs, Inventory (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesCapitalizedSoftwareDevelopmentCostsInventoryFyDetails Significant Accounting Policies, Capitalized Software Development Costs, Inventory (FY) (Details) Details 79 false false R80.htm 120220 - Disclosure - Significant Accounting Policies, Accrued Expenses and Other, Inventory (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesAccruedExpensesAndOtherInventoryFyDetails Significant Accounting Policies, Accrued Expenses and Other, Inventory (FY) (Details) Details 80 false false R81.htm 120222 - Disclosure - Significant Accounting Policies, Leases (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesLeasesFyDetails Significant Accounting Policies, Leases (FY) (Details) Details 81 false false R82.htm 120224 - Disclosure - Significant Accounting Policies, Advertising (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesAdvertisingFyDetails Significant Accounting Policies, Advertising (FY) (Details) Details 82 false false R83.htm 120226 - Disclosure - Significant Accounting Policies, Offering Costs (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesOfferingCostsFyDetails Significant Accounting Policies, Offering Costs (FY) (Details) Details 83 false false R84.htm 120228 - Disclosure - Significant Accounting Policies, Recent Accounting Pronouncements (FY) (Details) Sheet http://billtrust.com/role/SignificantAccountingPoliciesRecentAccountingPronouncementsFyDetails Significant Accounting Policies, Recent Accounting Pronouncements (FY) (Details) Details 84 false false R85.htm 120300 - Disclosure - Acquisitions, Second Phase (FY) (Details) Sheet http://billtrust.com/role/AcquisitionsSecondPhaseFyDetails Acquisitions, Second Phase (FY) (Details) Details 85 false false R86.htm 120302 - Disclosure - Acquisitions, Credit2B (FY) (Details) Sheet http://billtrust.com/role/AcquisitionsCredit2bFyDetails Acquisitions, Credit2B (FY) (Details) Details 86 false false R87.htm 120304 - Disclosure - Acquisitions, Contingent Consideration Liabilities (FY) (Details) Sheet http://billtrust.com/role/AcquisitionsContingentConsiderationLiabilitiesFyDetails Acquisitions, Contingent Consideration Liabilities (FY) (Details) Details 87 false false R88.htm 120400 - Disclosure - Revenue from Contracts with Customers (FY) (Details) Sheet http://billtrust.com/role/RevenueFromContractsWithCustomersFyDetails Revenue from Contracts with Customers (FY) (Details) Details http://billtrust.com/role/RevenueFromContractsWithCustomersFy 88 false false R89.htm 120500 - Disclosure - Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Recurring Basis (FY) (Details) Sheet http://billtrust.com/role/FairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisFyDetails Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Recurring Basis (FY) (Details) Details 89 false false R90.htm 120502 - Disclosure - Fair Value Measurements, Significant Unobservable Inputs (FY) (Details) Sheet http://billtrust.com/role/FairValueMeasurementsSignificantUnobservableInputsFyDetails Fair Value Measurements, Significant Unobservable Inputs (FY) (Details) Details 90 false false R91.htm 120600 - Disclosure - Goodwill and Intangible Assets, net, Changes in Goodwill (FY) (Details) Sheet http://billtrust.com/role/GoodwillAndIntangibleAssetsNetChangesInGoodwillFyDetails Goodwill and Intangible Assets, net, Changes in Goodwill (FY) (Details) Details 91 false false R92.htm 120602 - Disclosure - Goodwill and Intangible Assets, net, Intangible Assets (FY) (Details) Sheet http://billtrust.com/role/GoodwillAndIntangibleAssetsNetIntangibleAssetsFyDetails Goodwill and Intangible Assets, net, Intangible Assets (FY) (Details) Details 92 false false R93.htm 120604 - Disclosure - Goodwill and Intangible Assets, net, Estimated Amortization Expense (FY) (Details) Sheet http://billtrust.com/role/GoodwillAndIntangibleAssetsNetEstimatedAmortizationExpenseFyDetails Goodwill and Intangible Assets, net, Estimated Amortization Expense (FY) (Details) Details 93 false false R94.htm 120700 - Disclosure - Property and Equipment, net (FY) (Details) Sheet http://billtrust.com/role/PropertyAndEquipmentNetFyDetails Property and Equipment, net (FY) (Details) Details http://billtrust.com/role/PropertyAndEquipmentNetFyTables 94 false false R95.htm 120800 - Disclosure - Current and Long-Term Debt and Capital Lease Obligation, Current and Long-term Debt and Capital Lease Obligations (FY) (Details) Sheet http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationCurrentAndLongtermDebtAndCapitalLeaseObligationsFyDetails Current and Long-Term Debt and Capital Lease Obligation, Current and Long-term Debt and Capital Lease Obligations (FY) (Details) Details 95 false false R96.htm 120802 - Disclosure - Current and Long-Term Debt and Capital Lease Obligation, 2020 Financing Agreement (FY) (Details) Sheet http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligation2020FinancingAgreementFyDetails Current and Long-Term Debt and Capital Lease Obligation, 2020 Financing Agreement (FY) (Details) Details 96 false false R97.htm 120804 - Disclosure - Current and Long-Term Debt and Capital Lease Obligation, Loan Agreement and Credit Agreement (FY) (Details) Sheet http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationLoanAgreementAndCreditAgreementFyDetails Current and Long-Term Debt and Capital Lease Obligation, Loan Agreement and Credit Agreement (FY) (Details) Details 97 false false R98.htm 120806 - Disclosure - Current and Long-Term Debt and Capital Lease Obligation, Covenant Compliance and Capital Leases (FY) (Details) Sheet http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationCovenantComplianceAndCapitalLeasesFyDetails Current and Long-Term Debt and Capital Lease Obligation, Covenant Compliance and Capital Leases (FY) (Details) Details 98 false false R99.htm 120900 - Disclosure - Incentive Compensation Plans, Compensation Plans (FY) (Details) Sheet http://billtrust.com/role/IncentiveCompensationPlansCompensationPlansFyDetails Incentive Compensation Plans, Compensation Plans (FY) (Details) Details 99 false false R100.htm 120902 - Disclosure - Incentive Compensation Plans, Stock Options (FY) (Details) Sheet http://billtrust.com/role/IncentiveCompensationPlansStockOptionsFyDetails Incentive Compensation Plans, Stock Options (FY) (Details) Details 100 false false R101.htm 120904 - Disclosure - Incentive Compensation Plans, Stock Option Activity (FY) (Details) Sheet http://billtrust.com/role/IncentiveCompensationPlansStockOptionActivityFyDetails Incentive Compensation Plans, Stock Option Activity (FY) (Details) Details 101 false false R102.htm 120908 - Disclosure - Incentive Compensation Plans, Stock Compensation Expense (FY) (Details) Sheet http://billtrust.com/role/IncentiveCompensationPlansStockCompensationExpenseFyDetails Incentive Compensation Plans, Stock Compensation Expense (FY) (Details) Details 102 false false R103.htm 120910 - Disclosure - Incentive Compensation Plans, Defined Contribution Benefit Plan (FY) (Details) Sheet http://billtrust.com/role/IncentiveCompensationPlansDefinedContributionBenefitPlanFyDetails Incentive Compensation Plans, Defined Contribution Benefit Plan (FY) (Details) Details 103 false false R104.htm 121000 - Disclosure - Income Taxes (FY) (Details) Sheet http://billtrust.com/role/IncomeTaxesFyDetails Income Taxes (FY) (Details) Details http://billtrust.com/role/IncomeTaxesFyTables 104 false false R105.htm 121100 - Disclosure - Commitments and Contingencies (FY) (Details) Sheet http://billtrust.com/role/CommitmentsAndContingenciesFyDetails Commitments and Contingencies (FY) (Details) Details http://billtrust.com/role/CommitmentsAndContingenciesFyTables 105 false false R106.htm 121104 - Disclosure - Commitment and Contingencies, Future Minimum Lease Payments under Operating and Capital Leases (FY) (Details) Sheet http://billtrust.com/role/CommitmentAndContingenciesFutureMinimumLeasePaymentsUnderOperatingAndCapitalLeasesFyDetails Commitment and Contingencies, Future Minimum Lease Payments under Operating and Capital Leases (FY) (Details) Details 106 false false R107.htm 121200 - Disclosure - Segment Information (FY) (Details) Sheet http://billtrust.com/role/SegmentInformationFyDetails Segment Information (FY) (Details) Details http://billtrust.com/role/SegmentInformationFyTables 107 false false R108.htm 121300 - Disclosure - Related Party Transactions (FY) (Details) Sheet http://billtrust.com/role/RelatedPartyTransactionsFyDetails Related Party Transactions (FY) (Details) Details http://billtrust.com/role/RelatedPartyTransactionsFy 108 false false R109.htm 121400 - Disclosure - Loss per Share, Basic and Diluted (FY) (Details) Sheet http://billtrust.com/role/LossPerShareBasicAndDilutedFyDetails Loss per Share, Basic and Diluted (FY) (Details) Details 109 false false R110.htm 121402 - Disclosure - Loss per Share, Antidilutive (FY) (Details) Sheet http://billtrust.com/role/LossPerShareAntidilutiveFyDetails Loss per Share, Antidilutive (FY) (Details) Details 110 false false R111.htm 121502 - Disclosure - Subsequent Events (FY) (Details) Sheet http://billtrust.com/role/SubsequentEventsFyDetails Subsequent Events (FY) (Details) Details http://billtrust.com/role/SubsequentEventsFy 111 false false R112.htm 121600 - Disclosure - Organization and Nature of Business (Q1) (Details) Sheet http://billtrust.com/role/OrganizationAndNatureOfBusinessQ1Details Organization and Nature of Business (Q1) (Details) Details http://billtrust.com/role/OrganizationAndNatureOfBusinessFy 112 false false R113.htm 121700 - Disclosure - Summary of Significant Accounting Policies (Q1) (Details) Sheet http://billtrust.com/role/SummaryOfSignificantAccountingPoliciesQ1Details Summary of Significant Accounting Policies (Q1) (Details) Details http://billtrust.com/role/SummaryOfSignificantAccountingPoliciesQ1Tables 113 false false R114.htm 121800 - Disclosure - Contingent Consideration (Q1) (Details) Sheet http://billtrust.com/role/ContingentConsiderationQ1Details Contingent Consideration (Q1) (Details) Details http://billtrust.com/role/ContingentConsiderationQ1Tables 114 false false R115.htm 121900 - Disclosure - Business Combinations - Narrative (Q1) (Details) Sheet http://billtrust.com/role/BusinessCombinationsNarrativeQ1Details Business Combinations - Narrative (Q1) (Details) Details 115 false false R116.htm 121902 - Disclosure - Business Combination - Recapitalization (Q1) (Details) Sheet http://billtrust.com/role/BusinessCombinationRecapitalizationQ1Details Business Combination - Recapitalization (Q1) (Details) Details 116 false false R117.htm 121904 - Disclosure - Business Combination - Earnout Shares Reconciliation (Q1) (Details) Sheet http://billtrust.com/role/BusinessCombinationEarnoutSharesReconciliationQ1Details Business Combination - Earnout Shares Reconciliation (Q1) (Details) Details 117 false false R118.htm 122000 - Disclosure - Revenue from Contracts with Customers (Q1) (Details) Sheet http://billtrust.com/role/RevenueFromContractsWithCustomersQ1Details Revenue from Contracts with Customers (Q1) (Details) Details http://billtrust.com/role/RevenueFromContractsWithCustomersFy 118 false false R119.htm 122100 - Disclosure - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Q1) (Details) Sheet http://billtrust.com/role/FairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisQ1Details Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Q1) (Details) Details 119 false false R120.htm 122102 - Disclosure - Fair Value Measurements - Significant Unobservable Inputs (Q1) (Details) Sheet http://billtrust.com/role/FairValueMeasurementsSignificantUnobservableInputsQ1Details Fair Value Measurements - Significant Unobservable Inputs (Q1) (Details) Details 120 false false R121.htm 122200 - Disclosure - Goodwill and Intangible Assets, net - Goodwill (Q1) (Details) Sheet http://billtrust.com/role/GoodwillAndIntangibleAssetsNetGoodwillQ1Details Goodwill and Intangible Assets, net - Goodwill (Q1) (Details) Details 121 false false R122.htm 122202 - Disclosure - Goodwill and Intangible Assets, net - Intangible Assets (Q1) (Details) Sheet http://billtrust.com/role/GoodwillAndIntangibleAssetsNetIntangibleAssetsQ1Details Goodwill and Intangible Assets, net - Intangible Assets (Q1) (Details) Details 122 false false R123.htm 122204 - Disclosure - Goodwill and Intangible Assets, net - Amortization (Q1) (Details) Sheet http://billtrust.com/role/GoodwillAndIntangibleAssetsNetAmortizationQ1Details Goodwill and Intangible Assets, net - Amortization (Q1) (Details) Details 123 false false R124.htm 122300 - Disclosure - Property and Equipment, net (Q1) (Details) Sheet http://billtrust.com/role/PropertyAndEquipmentNetQ1Details Property and Equipment, net (Q1) (Details) Details http://billtrust.com/role/PropertyAndEquipmentNetFyTables 124 false false R125.htm 122400 - Disclosure - Current and Long-Term Debt and Capital Lease Obligation - Schedule of Long-Term Debt and Capital Lease (Q1) (Details) Sheet http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationScheduleOfLongtermDebtAndCapitalLeaseQ1Details Current and Long-Term Debt and Capital Lease Obligation - Schedule of Long-Term Debt and Capital Lease (Q1) (Details) Details 125 false false R126.htm 122402 - Disclosure - Current and Long-Term Debt and Capital Lease Obligation - Narrative (Q1) (Details) Sheet http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationNarrativeQ1Details Current and Long-Term Debt and Capital Lease Obligation - Narrative (Q1) (Details) Details http://billtrust.com/role/CurrentAndLongtermDebtAndCapitalLeaseObligationsFyTables 126 false false R127.htm 122500 - Disclosure - Stockholders' Equity, Warrants and Redeemable Preferred Stock (Q1) (Details) Sheet http://billtrust.com/role/StockholdersEquityWarrantsAndRedeemablePreferredStockQ1Details Stockholders' Equity, Warrants and Redeemable Preferred Stock (Q1) (Details) Details http://billtrust.com/role/StockholdersEquityWarrantsAndRedeemablePreferredStockQ1 127 false false R128.htm 122600 - Disclosure - Incentive Compensation Plans - Narrative (Q1) (Details) Sheet http://billtrust.com/role/IncentiveCompensationPlansNarrativeQ1Details Incentive Compensation Plans - Narrative (Q1) (Details) Details 128 false false R129.htm 122602 - Disclosure - Incentive Compensation Plans - Stock Option Valuation Assumptions (Q1) (Details) Sheet http://billtrust.com/role/IncentiveCompensationPlansStockOptionValuationAssumptionsQ1Details Incentive Compensation Plans - Stock Option Valuation Assumptions (Q1) (Details) Details 129 false false R130.htm 122604 - Disclosure - Incentive Compensation Plans - Allocated Share-Based Compensation Expense (Q1) (Details) Sheet http://billtrust.com/role/IncentiveCompensationPlansAllocatedSharebasedCompensationExpenseQ1Details Incentive Compensation Plans - Allocated Share-Based Compensation Expense (Q1) (Details) Details 130 false false R131.htm 122800 - Disclosure - Commitment and Contingencies - Narrative (Q1) (Details) Sheet http://billtrust.com/role/CommitmentAndContingenciesNarrativeQ1Details Commitment and Contingencies - Narrative (Q1) (Details) Details 131 false false R132.htm 122802 - Disclosure - Commitment and Contingencies - Minimum Lease Payments (Q1) (Details) Sheet http://billtrust.com/role/CommitmentAndContingenciesMinimumLeasePaymentsQ1Details Commitment and Contingencies - Minimum Lease Payments (Q1) (Details) Details 132 false false R133.htm 122900 - Disclosure - Segment Information (Q1) (Details) Sheet http://billtrust.com/role/SegmentInformationQ1Details Segment Information (Q1) (Details) Details http://billtrust.com/role/SegmentInformationFyTables 133 false false R134.htm 123000 - Disclosure - Related Party Transactions (Q1) (Details) Sheet http://billtrust.com/role/RelatedPartyTransactionsQ1Details Related Party Transactions (Q1) (Details) Details http://billtrust.com/role/RelatedPartyTransactionsFy 134 false false R135.htm 123100 - Disclosure - Loss Per Share - Basic and Diluted (Q1) (Details) Sheet http://billtrust.com/role/LossPerShareBasicAndDilutedQ1Details Loss Per Share - Basic and Diluted (Q1) (Details) Details 135 false false R136.htm 123102 - Disclosure - Loss Per Share - Antidilutive (Q1) (Details) Sheet http://billtrust.com/role/LossPerShareAntidilutiveQ1Details Loss Per Share - Antidilutive (Q1) (Details) Details 136 false false R137.htm 123200 - Disclosure - Accrued Expenses and Other (Q1) (Details) Sheet http://billtrust.com/role/AccruedExpensesAndOtherQ1Details Accrued Expenses and Other (Q1) (Details) Details http://billtrust.com/role/AccruedExpensesAndOtherQ1Tables 137 false false All Reports Book All Reports btrs-20210628.xml btrs-20210628.xsd btrs-20210628_cal.xml btrs-20210628_def.xml btrs-20210628_lab.xml btrs-20210628_pre.xml http://xbrl.sec.gov/dei/2021 http://fasb.org/srt/2021-01-31 http://fasb.org/us-gaap/2021-01-31 true true