Noninterest Income and Expense - Components of Other Noninterest Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended							9 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Service charges on deposit accounts	$ 2,885				$ 3,353			$ 8,299	$ 9,770
ATM and interchange fees	2,329				2,132			6,534	6,240
Other service fees	545				562			1,598	1,683
Mortgage banking service fees	419				434			1,260	1,280
Change in value of mortgage servicing rights	(88)				181			(620)	311
Total service charges and fees	6,090				6,662			17,071	19,284
Gain on sale of loans	509				1,083			1,487	4,967
Commissions on sale of non-deposit investment products	703				692			2,317	2,294
Increase in cash value of life insurance	490				531			1,287	1,337
Change in indemnification asset	14				(461)			(491)	(876)
Gain (loss) on sale of foreclosed assets	385				313			1,853	1,479
Sale of customer checks	97				97			296	280
Lease brokerage income	167				75			385	273
Gain (loss) on disposal of fixed assets	(10)				2			60	(12)
Other	144				133			496	450
Total other noninterest income	2,499				2,465			7,690	10,192
Total noninterest income	8,589	7,877	8,295	7,353	9,127	10,131	10,218	24,761	29,476
Mortgage loan servicing fees, net of change in fair value of mortgage loan servicing rights	331				615			640	1,591
Mortgage banking revenue	$ 840				$ 1,698			$ 2,127	$ 6,558