Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Quarterly Financial Data [Line Items]
Net revenues	$ 254,580		$ 253,636		$ 239,797		$ 220,599		$ 235,324		$ 228,332		$ 228,250		$ 219,523		$ 968,612	[1]	$ 911,429	[1]	$ 824,765	[1]
Cost of revenues	148,061		146,061		148,704		141,785		137,856		133,804		138,702		123,500		584,611		533,862		460,576
Gross Profit	106,519		107,575		91,093		78,814		97,468		94,528		89,548		96,023		384,001		377,567		364,189
Selling, general and administrative expenses	28,025		15,121		21,728		35,382		24,109		26,566		26,321		32,221		100,256		109,217		96,587
Income from operations	78,494		92,454		69,365		43,432		73,359		67,962		63,227		63,802		283,745		268,350		267,602
Other income (expense), net	14,004		10,227		9,887		9,338		15,906		10,657		12,175		11,785		43,456		50,523		18,220
Income before income taxes	92,498		102,681		79,252		52,770		89,265		78,619		75,402		75,587		327,201		318,873		285,822
Income tax expense	18,263	[2]	24,990	[2]	18,673	[2]	12,749	[2]	18,563	[3]	17,013	[3]	16,118	[3]	17,439	[3]	74,675	[2]	69,133	[3]	66,164
Net income	$ 74,235		$ 77,691		$ 60,579		$ 40,021		$ 70,702		$ 61,606		$ 59,284		$ 58,148		$ 252,526		$ 249,740		$ 219,658
Earnings per share, diluted	$ 0.88	[4]	$ 0.92	[4]	$ 0.72	[4]	$ 0.48	[4]	$ 0.84	[4]	$ 0.73	[4]	$ 0.71	[4]	$ 0.69	[4]	$ 3.00	[4]	$ 2.97	[4]	$ 2.62
Weighted average shares outstanding, diluted	84,204		84,131		84,135		84,127		84,055		83,968		83,916		83,944		84,149		83,971		83,764

[1] Net revenues are attributed to regions based upon customer location.

[2] The tax rate for the year ended December 31, 2015 was impacted by favorable adjustments of $1.10 million relating to the true up of tax provisions, upon the finalization of the India tax computation and $1.20 million, relating to the finalization of state tax and local tax matters in the fourth quarter. The company has provided tax charges of $0.84 million on account of valuation allowances against the minimum alternative tax.

[3] The tax rate for the year ended December 31, 2014 was impacted by a favorable adjustment of $1.20 million, which related to the true up of tax provisions, pursuant to finalization of the tax computation of Syntel India, which had arisen on account of setoff of inter units unabsorbed expenses in the fourth quarter. Further, a $0.86 million tax charge has arisen on account of the particular tax dispute raised during the year. The Company has provided tax charges of $1.63 million and $0.88 million on account of valuation allowances against deferred tax assets recognized on investments and the minimum alternative tax, respectively.

[4] Earnings per share for the quarter are computed independently and may not equal the earnings per share computed for the total year.