Securities - Schedule of Gross Realized Gains and Losses on the Sales and Calls of Securities (Detail) - USD ($) $ in Thousands	3 Months Ended							12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Securities Gross Realized Gain Loss [Abstract]
Gross realized gains								$ 2,638	$ 1,029	$ 1,131
Gross realized losses								(281)	(81)	(228)
Net realized gains	$ 63	$ 598	$ 585	$ 1,111	$ 880	$ 47	$ 22	$ 2,357	$ 948	$ 903