Investments in and Advances to Joint Ventures - Summary of Financial Information for Consolidated Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Schedule Of Equity Method Investments [Line Items]
Current assets	$ 1,583,626		$ 1,583,626		$ 1,632,351
Total assets	4,109,805		4,109,805		3,830,940
Current liabilities	1,098,786		1,098,786		1,030,784
Total liabilities	2,145,138		2,145,138		1,893,828
Total joint venture equity	1,928,181		1,928,181		1,900,768
Revenue	1,008,721	$ 879,356	1,957,790	$ 1,754,053
Costs	781,772	680,328	1,515,672	1,349,410
Net income attributable to Parsons Corporation	18,295	6,702	38,962	15,741
Net income attributable to noncontrolling interests	4,485	5,325	7,661	10,300
Consolidated Joint Ventures
Schedule Of Equity Method Investments [Line Items]
Current assets	232,052		232,052		246,342
Noncurrent assets	5,996		5,996		2,180
Total assets	238,048		238,048		248,522
Current liabilities	163,961		163,961		175,637
Total liabilities	163,961		163,961		175,637
Total joint venture equity	74,087		74,087		$ 72,885
Revenue	108,089	98,245	203,623	194,869
Costs	98,761	87,097	187,603	173,403
Net income attributable to Parsons Corporation	9,328	11,148	16,020	21,466
Net income attributable to noncontrolling interests	$ 4,485	$ 5,325	$ 7,661	$ 10,300