0001819394-21-000015 | 10-Q | XBRL Viewer

Reverse Recapitalization - Shares Issued Immediately following Consummation of Merger (Details)	Jul. 22, 2021 shares
Reverse Recapitalization [Line Items]
Earnout shares excluded (shares)	23,460,000
Earnout period	180 days

Label	Element	Value
Temporary Equity, Value, Conversion of Convertible Securities	mttr_TemporaryEquityValueConversionOfConvertibleSecurities	$ 164,461,000
Temporary Equity, Value, Conversion of Convertible Securities	mttr_TemporaryEquityValueConversionOfConvertibleSecurities	$ (9,501,000)
Number of Term Loan Facilities	mttr_NumberOfTermLoanFacilities	2
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Fair Value Adjustment	mttr_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityFairValueAdjustment	$ 98,478,000
Warrant Redemption, Number of Trading Days at or Above Trigger Price	mttr_WarrantRedemptionNumberOfTradingDaysAtOrAboveTriggerPrice	20
Class of Warrant or Right, Threshold Days For Transfer, Assignment or Sale of Warrants	mttr_ClassOfWarrantOrRightThresholdDaysForTransferAssignmentOrSaleOfWarrants	30 days
Temporary Equity, Dividend Rate	mttr_TemporaryEquityDividendRate	0.080
Temporary Equity, Dividend Rate	mttr_TemporaryEquityDividendRate	0.080
Temporary Equity, Dividend Rate	mttr_TemporaryEquityDividendRate	0.080
Temporary Equity, Dividend Rate	mttr_TemporaryEquityDividendRate	0.080
Temporary Equity, Dividend Rate	mttr_TemporaryEquityDividendRate	0.080
Payments to Acquire Debt Securities, Available-for-sale, Convertible Notes	mttr_PaymentsToAcquireDebtSecuritiesAvailableForSaleConvertibleNotes	$ 1,000,000
Payments to Acquire Debt Securities, Available-for-sale, Convertible Notes	mttr_PaymentsToAcquireDebtSecuritiesAvailableForSaleConvertibleNotes	0
Proceeds From Reverse Recapitalization	mttr_ProceedsFromReverseRecapitalization	612,854,000
Proceeds From Reverse Recapitalization	mttr_ProceedsFromReverseRecapitalization	$ 0
Debt Instrument, Number of Periodic Payments	mttr_DebtInstrumentNumberOfPeriodicPayments	36,000,000
Debt Instrument, Number of Periodic Payments	mttr_DebtInstrumentNumberOfPeriodicPayments	36,000,000
Debt Instrument, Number of Periodic Payments	mttr_DebtInstrumentNumberOfPeriodicPayments	36,000,000
Debt Instrument, Number of Periodic Payments	mttr_DebtInstrumentNumberOfPeriodicPayments	36
Debt Instrument, Number of Periodic Payments	mttr_DebtInstrumentNumberOfPeriodicPayments	24,000,000
Payments for Settlement of Vested Stock Options	mttr_PaymentsForSettlementOfVestedStockOptions	$ 0
Payments for Settlement of Vested Stock Options	mttr_PaymentsForSettlementOfVestedStockOptions	554,000
Aggregate Proceeds from Issuance of Equity and Conversion of Debt	mttr_AggregateProceedsFromIssuanceOfEquityAndConversionOfDebt	52,400,000
Reverse Recapitalization, Deferred Transaction Costs	mttr_ReverseRecapitalizationDeferredTransactionCosts	100,000
Note Receivable, Face Amount	mttr_NoteReceivableFaceAmount	1,000,000
Debt Instrument, Convertible, Terms of Conversion Feature, Qualified Financing, Threshold Aggregate Gross Proceeds Trigger	mttr_DebtInstrumentConvertibleTermsOfConversionFeatureQualifiedFinancingThresholdAggregateGrossProceedsTrigger	$ 10,000,000
Number of Business Days to Convert Credit Card Receivables to Cash	mttr_NumberOfBusinessDaysToConvertCreditCardReceivablesToCash	3
Number of Business Days to Convert Credit Card Receivables to Cash	mttr_NumberOfBusinessDaysToConvertCreditCardReceivablesToCash	5
Note Receivable, Stated Interest Rate	mttr_NoteReceivableStatedInterestRate	0.050
Temporary Equity, Shares, Conversion Of Convertible Securities	mttr_TemporaryEquitySharesConversionOfConvertibleSecurities	125,031,000
Temporary Equity, Shares, Conversion Of Convertible Securities	mttr_TemporaryEquitySharesConversionOfConvertibleSecurities	(4,729,000)
Debt Instrument, Convertible, Terms of Conversion Feature, Converted Instrument Amount, Discount Rate	mttr_DebtInstrumentConvertibleTermsOfConversionFeatureConvertedInstrumentAmountDiscountRate	0.100
Debt Instrument, Convertible, Terms of Conversion Feature, Converted Instrument Amount, Discount Rate	mttr_DebtInstrumentConvertibleTermsOfConversionFeatureConvertedInstrumentAmountDiscountRate	0.150
Payments to Acquire Debt Securities, Available-for-sale, Investments	mttr_PaymentsToAcquireDebtSecuritiesAvailableForSaleInvestments	$ 466,466,000
Payments to Acquire Debt Securities, Available-for-sale, Investments	mttr_PaymentsToAcquireDebtSecuritiesAvailableForSaleInvestments	0
Reverse Recapitalization, Contingent Earnout Liability Recognized	mttr_ReverseRecapitalizationContingentEarnoutLiabilityRecognized	231,627,000
Reverse Recapitalization, Contingent Earnout Liability Recognized	mttr_ReverseRecapitalizationContingentEarnoutLiabilityRecognized	$ 0
Warrant Redemption, Number of Trading Days Included in Fair Market Value Average	mttr_WarrantRedemptionNumberOfTradingDaysIncludedInFairMarketValueAverage	10
Stock Issued During Period, Shares, Warrants Exercised	mttr_StockIssuedDuringPeriodSharesWarrantsExercised	0
Stock Issued During Period, Shares, Warrants Exercised	mttr_StockIssuedDuringPeriodSharesWarrantsExercised	0
Stock Issued During Period, Shares, Warrants Exercised	mttr_StockIssuedDuringPeriodSharesWarrantsExercised	0
Class of Warrant or Right, Prior Written Notice of Redemption, Period	mttr_ClassOfWarrantOrRightPriorWrittenNoticeOfRedemptionPeriod	30 days
Number of Lenders	mttr_NumberOfLenders	3
Reverse Capitalization, Transaction Costs Paid	mttr_ReverseCapitalizationTransactionCostsPaid	$ 600,000
Reverse Recapitalization, Accrued Transaction Costs	mttr_ReverseRecapitalizationAccruedTransactionCosts	200,000
Reverse Recapitalization, Accrued Transaction Costs	mttr_ReverseRecapitalizationAccruedTransactionCosts	$ 135,000
Debt Instrument, Period of Interest-only Payments	mttr_DebtInstrumentPeriodOfInterestOnlyPayments	12 months
Class of Warrant or Right, Redemption, Period After Warrants Become Exercisable	mttr_ClassOfWarrantOrRightRedemptionPeriodAfterWarrantsBecomeExercisable	90 days
Adjustments to Additional Paid In Capital, Options Settled With Cash	mttr_AdjustmentsToAdditionalPaidInCapitalOptionsSettledWithCash	$ 554,000
Adjustments to Additional Paid In Capital, Options Settled With Cash	mttr_AdjustmentsToAdditionalPaidInCapitalOptionsSettledWithCash	554,000
Debt Instrument, Aggregated Annual Coupon Payment	mttr_DebtInstrumentAggregatedAnnualCouponPayment	100,000
Accrued Liabilities and Other Liabilities, Current	mttr_AccruedLiabilitiesAndOtherLiabilitiesCurrent	8,781,000
Accrued Liabilities and Other Liabilities, Current	mttr_AccruedLiabilitiesAndOtherLiabilitiesCurrent	$ 6,995,000
Stock Issued During Period, Shares, Exercise of Warrants	mttr_StockIssuedDuringPeriodSharesExerciseOfWarrants	1,038,000
Payment of Final Payment Fee	mttr_PaymentOfFinalPaymentFee	$ 500,000
Stock Issued During Period, Value, Reverse Recapitalization	mttr_StockIssuedDuringPeriodValueReverseRecapitalization	7,000
Stock Issued During Period, Value, Reverse Recapitalization	mttr_StockIssuedDuringPeriodValueReverseRecapitalization	539,890,000
Stock Issued During Period, Value, Reverse Recapitalization	mttr_StockIssuedDuringPeriodValueReverseRecapitalization	539,897,000
Accounts Receivable, Net, Excluding Unbilled Receivables	mttr_AccountsReceivableNetExcludingUnbilledReceivables	7,793,000
Accounts Receivable, Net, Excluding Unbilled Receivables	mttr_AccountsReceivableNetExcludingUnbilledReceivables	2,700,000
Accrued Liabilities, Other Miscellaneous, Current	mttr_AccruedLiabilitiesOtherMiscellaneousCurrent	5,133,000
Accrued Liabilities, Other Miscellaneous, Current	mttr_AccruedLiabilitiesOtherMiscellaneousCurrent	2,488,000
Reverse Recapitalization Transaction Costs Incurred But Not Yet Paid	mttr_ReverseRecapitalizationTransactionCostsIncurredButNotYetPaid	200,000
Reverse Recapitalization Transaction Costs Incurred But Not Yet Paid	mttr_ReverseRecapitalizationTransactionCostsIncurredButNotYetPaid	$ 0
Debt Instrument, Number of Monthly Payments	mttr_DebtInstrumentNumberOfMonthlyPayments	48
Warrant Redemption, Days Included in Redemption Trading Day Period	mttr_WarrantRedemptionDaysIncludedInRedemptionTradingDayPeriod	30
Adjustments to Additional Paid in Capital, Contingent Earn-Out Liability	mttr_AdjustmentsToAdditionalPaidInCapitalContingentEarnOutLiability	$ 235,911,000
Adjustments to Additional Paid in Capital, Contingent Earn-Out Liability	mttr_AdjustmentsToAdditionalPaidInCapitalContingentEarnOutLiability	235,911,000
Debt Securities, Available For Sale, Maturity, After One Through Three Years Amortized Cost	mttr_DebtSecuritiesAvailableForSaleMaturityAfterOneThroughThreeYearsAmortizedCost	$ 292,081,000
Share-based Compensation Arrangement by Share-based Payment Award, Modified Options, Outstanding, Number	mttr_ShareBasedCompensationArrangementByShareBasedPaymentAwardModifiedOptionsOutstandingNumber	866,597
Debt securities, Available For Sale, Maturity After One Through three Years Fair Value	mttr_DebtSecuritiesAvailableForSaleMaturityAfterOneThroughThreeYearsFairValue	$ 291,996,000
Common Stock and Preferred Stock, Shares Authorized	mttr_CommonStockAndPreferredStockSharesAuthorized	670,000,000
Long-term Debt, Net of Unamortized Debt Discount	mttr_LongTermDebtNetOfUnamortizedDebtDiscount	$ 12,717,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Reallocation of Earn-out Shares to Earn-out Liability upon Forfeitures	mttr_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityReallocationOfEarnOutSharesToEarnOutLiabilityUponForfeitures	$ 4,284,000

Contingent Earn-out Awards - Narrative (Details) $ in Millions	Jul. 22, 2021 USD ($) d tranche shares
Reverse Recapitalization [Line Items]
Earn-out (shares)	23,460,000
Number of tranches of earn-out shares \| tranche	6
Earn-out share release, number of trading days above trigger price \| d	10
Earn-out share release, number of consecutive trading days in trigger period \| d	30
Equity earn-out period start, number of days after Closing \| d	180
Estimated fair value of total earn-out shares at Closing \| $	$ 294.8
Weighted Average Share Price in Excess of $13.00
Reverse Recapitalization [Line Items]
Earn-out (shares)	3,910,000
Weighted Average Share Price in Excess of $15.50
Reverse Recapitalization [Line Items]
Earn-out (shares)	3,910,000
Weighted Average Share Price in Excess of $18.00
Reverse Recapitalization [Line Items]
Earn-out (shares)	3,910,000
Weighted Average Share Price in Excess of $20.50
Reverse Recapitalization [Line Items]
Earn-out (shares)	3,910,000
Weighted Average Share Price in Excess of $23.00
Reverse Recapitalization [Line Items]
Earn-out (shares)	3,910,000
Weighted Average Share Price in Excess of $25.50
Reverse Recapitalization [Line Items]
Earn-out (shares)	3,910,000

Reverse Recapitalization - Narrative (Details) $ in Thousands			3 Months Ended			9 Months Ended
	Jul. 22, 2021 USD ($) shares	Jul. 21, 2021 shares	Sep. 30, 2021 USD ($) shares	Sep. 30, 2020 USD ($)	Jun. 30, 2020 shares	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Reverse Recapitalization [Line Items]
Gross proceeds received in business combination	$ 640,100
Proceeds from cash held in trust account	345,100
Transaction costs paid	36,300					$ 9,813	$ 0
Additional paid in capital, reduction of proceeds	35,700
Transaction costs	$ 600		$ 565	$ 0		$ 565	$ 0
Issuance of common stock (shares) \| shares	72,500,000		72,531,000
Recapitalization exchange ratio	4.1193	4.1193
Issuance of Series D redeemable convertible preferred stocks net of issuance costs (shares) \| shares		52,236	52,000		21,708,000

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Notes Details Reverse Recapitalization - Narrative (Details) Reverse Recapitalization - Shares Issued Immediately following Consummation of Merger (Details) Contingent Earn-out Awards - Narrative (Details) Uncategorized Uncategorized Items - mttr-20210930_htm.xml All Reports