Expected Goodwill Tax Amortization Period

No definition available.

Name:	mant_ExpectedGoodwillTaxAmortizationPeriod
Namespace Prefix:	mant_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

+ Details

Name:	us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477

+ Details

Name:	us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

For transactions that are recognized separately from the acquisition of assets and assumptions of liabilities in the business combination, such as related to pre-existing relationships with the acquiree, this element represents the disclosure of the amount of acquisition related costs which have been expensed.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

Name:	us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

+ Details

Name:	us-gaap_FinitelivedIntangibleAssetsAcquired1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=120320667&loc=SL49117168-202975

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

+ Details

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

- Details

Name:	us-gaap_BusinessAcquisitionAxis=mant_TMACMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_OrderOrProductionBacklogMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=mant_GryphonTechnologiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=mant_TapestryTechnologiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=mant_MinervaEngineeringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Acquisitions (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Acquisitions (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Goodwill	$ 1,498,988	$ 1,237,894	$ 1,191,259
TMAC
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	30,200
Goodwill	$ 13,200
ExpectedGoodwillTaxAmortizationPeriod	15 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	19 years
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed	$ 400
TMAC \| Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 15,300
Finite-Lived Intangible Asset, Useful Life	20 years
TMAC \| Backlog [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 700
Finite-Lived Intangible Asset, Useful Life	1 year
Gryphon Technologies
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 360,800
Goodwill	$ 247,632
ExpectedGoodwillTaxAmortizationPeriod	13 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	19 years
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed	$ 1,100
Gryphon Technologies \| Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 65,800
Finite-Lived Intangible Asset, Useful Life	20 years
Gryphon Technologies \| Backlog [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 5,500
Finite-Lived Intangible Asset, Useful Life	2 years
Tapestry Technologies
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 46,300
Goodwill	$ 27,000
ExpectedGoodwillTaxAmortizationPeriod	15 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	18 years
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed		100
Tapestry Technologies \| Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 15,100
Finite-Lived Intangible Asset, Useful Life	20 years
Tapestry Technologies \| Backlog [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 1,400
Finite-Lived Intangible Asset, Useful Life	2 years
Minerva Engineering [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 32,700
Goodwill	$ 19,800
ExpectedGoodwillTaxAmortizationPeriod	15 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	18 years
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed		$ 400
Minerva Engineering [Member] \| Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 10,500
Finite-Lived Intangible Asset, Useful Life	20 years
Minerva Engineering [Member] \| Backlog [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 1,100
Finite-Lived Intangible Asset, Useful Life	2 years