Convertible Senior Notes - Change in Fair Value of Embedded Conversion Derivative (Details) - Convertible Debt - 2026 Notes - Embedded conversion derivative $ in Thousands	6 Months Ended
Mar. 31, 2022 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 48,208
Remeasurement to fair value on March 3, 2022	(19,692)
Impact of increase of authorized shares of common stock on convertible senior notes hedge	(28,516)
Ending Balance	$ 0

Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Liability, Increase (Decrease) Due To Increase Of Authorized Shares Of Common Stock

No definition available.

+ Details

Name:	mitk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIncreaseDecreaseDueToIncreaseOfAuthorizedSharesOfCommonStock
Namespace Prefix:	mitk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Liability, Increase (Decrease) Due To Remeasurement To Fair Value

+ References

No definition available.

+ Details

Name:	mitk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIncreaseDecreaseDueToRemeasurementToFairValue
Namespace Prefix:	mitk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_ConvertibleDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mitk_ConvertibleSeniorUnsecuredNotesDue2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_EmbeddedDerivativeFinancialInstrumentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: