Income Taxes (Fringe Benefit Tax And Syntel Europe Limited Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Syntel Europe Limited [Member]	Dec. 31, 2011 Syntel Europe Limited [Member]	Dec. 31, 2010 Syntel Europe Limited [Member]
Operating Loss Carryforwards [Line Items]
Fringe benefit tax rate	33.99%
Fringe benefit tax expense, reversed		$ 1.07
Fringe benefit tax refund	0.38
Incurred losses of subsidiary			1.06	0.79
Refund claim					0.19
Deferred tax assets			$ 0.28