Segment Information - Summary of Adjusted EBITDA Business Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Adjusted EBITDA attributable to Parsons Corporation
Adjusted EBITDA attributable to Parsons Corporation	$ 125,504	$ 80,505
Adjusted EBITDA attributable to noncontrolling interests	15,589	9,886
Depreciation and amortization	(24,531)	(28,359)
Interest expense, net	(11,846)	(5,665)
Income tax benefit (expense)	32,234	(11,503)
Equity-based compensation expense	(12,656)	(6,703)
Loss on extinguishment of debt	211,018	0
Transaction-related costs	(2,886)	(1,618)
Restructuring expense	0	(546)
Other	(2,502)	(721)
Net (loss) income including noncontrolling interests	(92,112)	35,276
Net income attributable to noncontrolling interests	15,243	9,723
Net (loss) income attributable to Parsons Corporation	(107,355)	25,553
Federal Solution Segment
Adjusted EBITDA attributable to Parsons Corporation
Adjusted EBITDA attributable to Parsons Corporation	92,541	56,148
Critical Infrastructure
Adjusted EBITDA attributable to Parsons Corporation
Adjusted EBITDA attributable to Parsons Corporation	$ 32,963	$ 24,357