Other Comprehensive Income - Summary of Other Comprehensive Income and Tax Impact (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract]
Net unrealized (loss) gain on available-for-sale securities, net of income taxes	$ (330)	$ 89
Net unrealized gain on interest rate swaps, net of income taxes	450	93
Foreign currency translation	(6)	(2)
Total other comprehensive income	$ 114	$ 180