Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income (loss)	$ (146)	$ (45)	$ (105)	$ (37)
Unrealized Gains (Losses) on Debt Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income (loss), before tax amount	(207)	(89)	(156)	(81)
Amounts reclassified from accumulated other comprehensive income (loss), tax expense (benefit)	63	26	47	23
Amounts reclassified from accumulated other comprehensive income (loss)	(144)	(63)	(109)	(58)
Defined Benefit Pension Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income (loss), before tax amount	(1)	24	7	32
Amounts reclassified from accumulated other comprehensive income (loss), tax expense (benefit)	(1)	(6)	(3)	(11)
Amounts reclassified from accumulated other comprehensive income (loss)	$ (2)	$ 18	$ 4	$ 21

SYNTEL INC 10-Q