Noninterest Income and Expense - Components of Other Noninterest Income (Detail) - USD ($) $ in Thousands	3 Months Ended							9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Service charges on deposit accounts	$ 3,641				$ 3,642			$ 10,549	$ 10,879
ATM and interchange fees	3,851				3,344			11,136	9,729
Other service fees	792				772			2,369	2,265
Mortgage banking service fees	537				521			1,570	1,583
Change in value of mortgage servicing rights	(799)				(585)			(2,198)	(570)
Total service charges and fees	8,022				7,694			23,426	23,886
Gain on sale of loans	953				722			2,645	2,181
Commissions on sale of non-deposit investment products	747				812			1,890	2,561
Increase in cash value of life insurance	709				770			2,086	2,121
Change in indemnification asset	(10)				(26)			(274)	(148)
Gain (loss) on sale of foreclosed assets	69				356			218	782
Sale of customer checks	110				129			299	378
Lease brokerage income	172				161			602	543
Gain (loss) on disposal of fixed assets	(13)				(42)			(52)	(125)
Life Insurance death benefit in excess of cash value								238
Other	307				1,066			1,023	1,723
Total other noninterest income	3,044				3,948			8,675	10,016
Total noninterest income	11,066	$ 11,245	$ 9,790	$ 11,445	11,642	$ 12,080	$ 10,180	32,101	33,902
Mortgage loan servicing fees, net of change in fair value of mortgage loan servicing rights	(262)				(64)			(628)	1,013
Mortgage banking revenue	$ 691				$ 658			$ 2,017	$ 3,194