Investments in and Advances to Joint Ventures - Summary of Financial Information for Consolidated Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Schedule Of Equity Method Investments [Line Items]
Current assets	$ 1,640,966		$ 1,632,351
Total assets	3,808,841		3,830,940
Current liabilities	1,008,855		1,030,784
Total liabilities	1,858,216		1,893,828
Total joint venture equity	1,918,187		1,900,768
Revenue	949,069	$ 874,697
Costs	733,900	669,082
Net income attributable to Parsons Corporation	20,667	9,039
Net income attributable to noncontrolling interests	3,176	4,975
Consolidated Joint Ventures
Schedule Of Equity Method Investments [Line Items]
Current assets	214,229		246,342
Noncurrent assets	2,338		2,180
Total assets	216,567		248,522
Current liabilities	150,474		175,637
Total liabilities	150,474		175,637
Total joint venture equity	66,093		$ 72,885
Revenue	95,534	96,624
Costs	88,842	86,306
Net income attributable to Parsons Corporation	6,692	10,318
Net income attributable to noncontrolling interests	$ 3,176	$ 4,975