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	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Numerator for Basic and Diluted EPS:
Net income (loss) attributable to Parsons Corporation	$ 71,951	$ 47,447	$ 33,768	$ 116,241
Convertible senior notes if-converted method interest adjustment	54	559	0	1,665
Diluted net income (loss) attributable to Parsons Corporation	$ 72,005	$ 48,006	$ 33,768	$ 117,906
Denominator for Basic and Diluted EPS:
Basic weighted average number of shares outstanding	106,291	104,971	106,211	104,894
Dilutive effect of stock-based awards	1,661	1,178	1,628	1,020
Dilutive effect of warrants	561		358
Dilutive effect of convertible senior notes due 2025	2,573	8,917	0	8,917
Diluted weighted average number of shares outstanding	111,086	115,066	108,197	114,831
Earnings (loss) per share:
Basic	$ 0.68	$ 0.45	$ 0.32	$ 1.11
Diluted	$ 0.65	$ 0.42	$ 0.31	$ 1.03

Denominator for basic and diluted EPS.

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