| Document and Entity Information | Dec. 03, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | FTI CONSULTING, INC |
| Entity Address, State or Province | DC |
| Amendment Flag | false |
| Entity Central Index Key | 0000887936 |
| Document Type | 8-K |
| Document Period End Date | Dec. 3, 2020 |
| Entity Incorporation State Country Code | MD |
| Entity File Number | 001-14875 |
| Entity Tax Identification Number | 52-1261113 |
| Entity Address, Address Line One | 555 12th Street NW |
| Entity Address, City or Town | Washington |
| Entity Address, Postal Zip Code | 20004 |
| City Area Code | (202) |
| Local Phone Number | 312-9100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, par value $0.01 per share |
| Trading Symbol | FCN |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
