Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 321,673	$ 509,457
Other comprehensive income	88	259
Ending Balance	552,388	505,386
Unrealized Gains and (Losses) on Securities Available-for- Sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(224)	(465)
Other comprehensive income (loss), before reclassifications	88	160
Amounts reclassified from accumulated other comprehensive income	0	0
Other comprehensive income	88	160
Ending Balance	(136)	(305)
Other comprehensive income (loss), before reclassifications, tax	(54)	(97)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		(569)
Other comprehensive income (loss), before reclassifications		99
Amounts reclassified from accumulated other comprehensive income		0
Other comprehensive income		99
Ending Balance		(470)
Other comprehensive income (loss), before reclassifications, tax		$ (61)