Goodwill - Summary of Changes in Carrying Value of Goodwill by Reporting Segment (Details) $ in Thousands	6 Months Ended
Jun. 30, 2021 USD ($)
Goodwill [Line Items]
Beginning Balance	$ 1,261,978
Acquisitions	(1,292)
Foreign Exchange	2,374
Ending Balance	1,263,060
Federal Solutions
Goodwill [Line Items]
Beginning Balance	1,188,882
Acquisitions	(1,292)
Ending Balance	1,187,590
Critical Infrastructure
Goodwill [Line Items]
Beginning Balance	73,096
Foreign Exchange	2,374
Ending Balance	$ 75,470

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.

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
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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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