Earnings Per Share - Schedule of Denominator and Numerator used to Compute Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Numerator for Basic and Diluted EPS:
Net income (loss) attributable to Parsons Corporation	$ 69,172	$ 43,241	$ (38,183)	$ 68,794
Convertible senior notes if-converted method interest adjustment	54	554	0	1,106
Diluted net income (loss) attributable to Parsons Corporation	$ 69,226	$ 43,795	$ (38,183)	$ 69,900
Denominator for Basic and Diluted EPS:
Basic weighted average number of shares outstanding	106,303	104,908	106,170	104,856
Dilutive effect of stock-based awards	1,233	883	0	941
Dilutive effect of warrants	415
Dilutive effect of convertible senior notes due 2025	2,573	8,917	0	8,917
Diluted weighted average number of shares outstanding	110,524	114,708	106,170	114,714
Earnings (loss) per share:
Basic	$ 0.65	$ 0.41	$ (0.36)	$ 0.66
Diluted	$ 0.63	$ 0.38	$ (0.36)	$ 0.61