Noninterest Income and Expense - Components of Other Noninterest Income (Detail) - USD ($) $ in Thousands	3 Months Ended						6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Service charges on deposit accounts	$ 3,543				$ 3,637		$ 6,908	$ 7,237
ATM and interchange fees	3,892				3,383		7,285	6,385
Other service fees	849				779		1,577	1,493
Mortgage banking service fees	516				528		1,033	1,062
Change in value of mortgage servicing rights	(701)				521		(1,399)	15
Total service charges and fees	8,099				8,848		15,404	16,192
Gain on sale of loans	889				837		1,692	1,459
Commissions on sale of non-deposit investment products	611				784		1,143	1,749
Increase in cash value of life insurance	681				675		1,377	1,350
Change in indemnification asset	(149)				(57)		(264)	(122)
Gain (loss) on sale of foreclosed assets	57				115		149	426
Sale of customer checks	70				121		189	249
Lease brokerage income	235				245		430	382
(Loss) gain on disposal of fixed assets	(8)				1		(39)	(83)
Other	760				511		954	658
Total other noninterest income	3,146				3,232		5,631	6,068
Total noninterest income	11,245	$ 9,790	$ 11,445	$ 11,642	12,080	$ 10,180	21,035	22,260
Mortgage loan servicing fees, net of change in fair value of mortgage loan servicing rights	$ (185)				$ 1,049		$ (366)	$ 1,077