No definition available.

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

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as noncurrent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(12))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479668/805-30-25-6

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 35
-Paragraph 1
-Subparagraph b
-SubTopic 30
-Topic 805
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479613/805-30-35-1

+ Details

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

- Definition

Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=mitk_NonUSGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

INVESTMENTS - Summary of Fair Value of Investments Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022
Assets:
Short-term investments:	$ 40,651	$ 58,268
Long-term investments:	2,815	10,633
Total assets at fair value	43,466	68,901
Liabilities:
Acquisition-related contingent consideration	8,013	5,920	$ 5,900
Total liabilities at fair value	8,013	5,920
U.S. Treasury
Assets:
Short-term investments:	22,039	5,882
Long-term investments:	1,296	3,221
Commercial paper
Assets:
Short-term investments:	6,155	18,022
Foreign government and agency securities
Assets:
Short-term investments:		2,827
Corporate debt securities
Assets:
Short-term investments:	12,457	31,537
Long-term investments:	1,519	7,412
Quoted Prices in Active Markets (Level 1)
Assets:
Short-term investments:	22,039	5,882
Long-term investments:	1,296	3,221
Total assets at fair value	23,335	9,103
Liabilities:
Acquisition-related contingent consideration	0	0
Total liabilities at fair value	0	0
Quoted Prices in Active Markets (Level 1) \| U.S. Treasury
Assets:
Short-term investments:	22,039	5,882
Long-term investments:	1,296	3,221
Quoted Prices in Active Markets (Level 1) \| Commercial paper
Assets:
Short-term investments:	0	0
Quoted Prices in Active Markets (Level 1) \| Foreign government and agency securities
Assets:
Short-term investments:		0
Quoted Prices in Active Markets (Level 1) \| Corporate debt securities
Assets:
Short-term investments:	0	0
Long-term investments:	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Short-term investments:	18,612	52,386
Long-term investments:	1,519	7,412
Total assets at fair value	20,131	59,798
Liabilities:
Acquisition-related contingent consideration	8,013	0
Total liabilities at fair value	8,013	0
Significant Other Observable Inputs (Level 2) \| U.S. Treasury
Assets:
Short-term investments:	0	0
Long-term investments:	0	0
Significant Other Observable Inputs (Level 2) \| Commercial paper
Assets:
Short-term investments:	6,155	18,022
Significant Other Observable Inputs (Level 2) \| Foreign government and agency securities
Assets:
Short-term investments:		2,827
Significant Other Observable Inputs (Level 2) \| Corporate debt securities
Assets:
Short-term investments:	12,457	31,537
Long-term investments:	1,519	7,412
Significant Unobservable Inputs (Level 3)
Assets:
Short-term investments:	0	0
Long-term investments:	0	0
Total assets at fair value	0	0
Liabilities:
Acquisition-related contingent consideration	0	5,920
Total liabilities at fair value	0	5,920
Significant Unobservable Inputs (Level 3) \| U.S. Treasury
Assets:
Short-term investments:	0	0
Long-term investments:	0	0
Significant Unobservable Inputs (Level 3) \| Commercial paper
Assets:
Short-term investments:	0	0
Significant Unobservable Inputs (Level 3) \| Foreign government and agency securities
Assets:
Short-term investments:		0
Significant Unobservable Inputs (Level 3) \| Corporate debt securities
Assets:
Short-term investments:	0	0
Long-term investments:	$ 0	$ 0