Schedule of Components of Income Tax (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Schedule Of Income Taxes [Line Items]
Current, Federal																	$ 8,904		$ 8,932		$ 5,913
Current, State																	1,686		1,609		1,064
Current, City																	281		268
Current, Foreign																	65,187		61,182		54,419
Total current provision																	76,058		71,991		61,396
Deferred, Federal																	(1,328)		(3)		(422)
Deferred, State																	(245)				(77)
Deferred, City																	(41)
Deferred, Foreign																	(5,311)		(5,824)		(6,512)
Total deferred (benefit)																	(6,925)		(5,827)		(7,011)
Total provision for income taxes	$ 18,563	[1]	$ 17,013	[1]	$ 16,118	[1]	$ 17,439	[1]	$ 18,856	[2]	$ 16,800	[2]	$ 16,044	[2]	$ 14,464	[2]	$ 69,133	[1]	$ 66,164	[2]	$ 54,385

[1] 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 Limited, which had arisen on account of setoff of inter units unabsorbed expenses. 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. Without the above, the effective tax rate for the year ended December 31, 2014 would have been 21.1%.

[2] The tax rate for the year ended December 31, 2013 was impacted by a favorable adjustment of $1.09 million which related to the true up of tax provisions, pursuant to finalization of the tax computation for filing tax returns of Syntel Limited, which had arisen on account of finalization of the actual numbers of expenses apportionment, wage reconciliations, meal disallowances etc., compared with the amounts estimated earlier for the tax provisions. Further, a $0.43 million reversal of tax reserve has arisen on account of the reversal of a valuation allowance, created in the past, and against deferred tax assets recognized on the allowance on the accumulated losses. During the year ended December 31, 2013, the Company reviewed the filing requirements for certain U.S. State and City income tax returns. The Company has updated the profit apportionment method in those certain states and cities. Accordingly, the Company had provided $1.59 million, out of which $0.6 million relates to the prior years. Without the above, the effective tax rate for the year ended December 31, 2013 would have been 23.5%.