Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 27, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Trading Symbol	PSN
Entity Registrant Name	Parsons Corporation
Entity Central Index Key	0000275880
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		100,669,694
Entity File Number	001-07782
Entity Tax Identification Number	95-3232481
Entity Address, Address Line One	5875 Trinity Parkway #300
Entity Address, City or Town	Centreville
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	20120
City Area Code	703
Local Phone Number	988-8500
Title of 12(b) Security	Common Stock, $1 par value
Security Exchange Name	NYSE
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes