| Document and Entity Information | Nov. 03, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 3, 2021 |
| Entity Registrant Name | PARSONS CORPORATION |
| Entity Central Index Key | 0000275880 |
| Entity Emerging Growth Company | false |
| Entity File Number | 001-07782 |
| Entity Incorporation State Country Code | DE |
| Entity Tax Identification Number | 95-3232481 |
| Entity Address, Address Line One | 5875 Trinity Parkway |
| Entity Address, Address Line Two | #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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $1 par value |
| Trading Symbol | PSN |
| Security Exchange Name | NYSE |
