Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Total net revenues	$ 681,747	$ 648,783	$ 630,523	$ 609,703	$ 646,528	$ 617,831	$ 609,532	$ 587,153	$ 2,570,756	$ 2,461,044	$ 2,279,438
Gross profit	276,075	256,351	246,768	236,855	252,591	242,001	243,228	229,677	1,016,049	967,497	901,350
Income from operations	98,092	87,124	79,940	75,622	83,446	87,343	89,353	74,050	340,777	334,192	294,031
Income before equity method investment activity, net and income tax expense	95,502	87,360	81,818	72,664	84,686	89,685	80,245	57,938	337,343	312,554	254,385
Net income (loss)	76,878	68,045	64,349	58,276	64,413	68,050	62,701	44,653	267,547	239,817	192,171
Net income attributable to non-controlling interest/redeemable Non-controlling interest	232	734	882	289					(2,137)		169
Net income attributable to Genpact Limited common shareholders	$ 77,110	$ 68,779	$ 65,231	$ 58,565	$ 64,413	$ 68,050	$ 62,701	$ 44,653	$ 269,684	$ 239,817	$ 192,002
Earnings per common share attributable to Genpact Limited common shareholders
Basic	$ 0.38	$ 0.33	$ 0.31	$ 0.28	$ 0.30	$ 0.32	$ 0.29	$ 0.20	$ 1.30	$ 1.11	$ 0.87
Diluted	$ 0.38	$ 0.33	$ 0.31	$ 0.27	$ 0.30	$ 0.31	$ 0.28	$ 0.20	$ 1.28	$ 1.09	$ 0.85
Weighted average number of common shares used in computing earnings per common share attributable to Genpact Limited common shareholders
Basic	200,341,922	206,146,007	210,178,050	210,780,165	212,697,001	215,311,322	218,525,149	219,892,695	206,861,536	216,606,542	220,847,098
Diluted	203,431,310	209,376,683	213,803,134	213,892,964	215,675,065	217,595,704	220,962,306	222,347,101	210,126,023	219,145,044	225,168,665