| Document and Entity Information | Mar. 23, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | Genpact LTD |
| Amendment Flag | false |
| Entity Central Index Key | 0001398659 |
| Document Type | 8-K |
| Document Period End Date | Mar. 23, 2021 |
| Entity Incorporation State Country Code | D0 |
| Entity File Number | 001-33626 |
| Entity Tax Identification Number | 98-0533350 |
| Entity Address, Address Line One | Canon’s Court |
| Entity Address, Address Line Two | 22 Victoria Street |
| Entity Address, City or Town | Hamilton |
| Entity Address, Postal Zip Code | HM 12 |
| Entity Address, Country | BM |
| City Area Code | (441) |
| Local Phone Number | 298-3300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common shares, par value $0.01 per share |
| Trading Symbol | G |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
