Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share (Abstract)
Net income available to Genpact Limited common shareholders	$ 70,262	$ 25,175	$ 180,875	$ 124,815
Weighted average number of common shares used in computing basic earnings per common share	230,057,508	223,876,035	228,840,746	223,289,507
Dilutive effect of stock-based awards	6,279,416	6,319,799	6,254,914	5,226,884
Weighted average number of common shares used in computing dilutive earnings per common share	236,336,924	230,195,834	235,095,660	228,516,391
Earnings per common share attributable to Genpact Limited common shareholders, Basic	$ 0.31	$ 0.11	$ 0.79	$ 0.56
Earnings per common share attributable to Genpact Limited common shareholders, Diluted	$ 0.30	$ 0.11	$ 0.77	$ 0.55

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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