Summary of Significant Accounting Policies - Components of Other Comprehensive Income and Related Tax Effects (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax [Abstract]
Net unrealized gain (loss) on available-for-sale securities	$ 100	$ 1,158	$ (8,448)
Reclassification adjustment for gain on sale of available-for-sale securities	(451)	(494)	(775)
Net unrealized gain (loss) on available for sale securities	(351)	664	(9,223)
Tax expense (benefit)	(119)	226	(3,136)
Other comprehensive income (loss)	$ (232)	$ 438	$ (6,087)