Noninterest Income and Expense - Components of Other Noninterest Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Statement [Abstract]
Service charges on deposit accounts										$ 12,716	$ 14,290	$ 14,776
ATM and interchange fees										8,370	7,762	7,058
Other service fees										2,144	2,223	1,722
Mortgage banking service fees										1,774	1,666	1,495
Change in value of mortgage servicing rights										253	(2,016)	(1,107)
Total service charges and fees										25,257	23,925	23,944
Gain on sale of loans										5,602	6,810	3,037
Commissions on sale of non-deposit investment products										2,983	3,209	2,105
Increase in cash value of life insurance										1,727	1,820	1,885
Change in indemnification asset										(1,649)	(286)	2,059
Gain on sale of foreclosed assets										1,640	786	680
Bargain purchase gain												7,575
Sale of customer checks										377	346	271
Lease brokerage income										337	276	248
Loss on disposal of fixed assets										(39)	(420)	(15)
Commission rebates											(56)	(58)
Gain on life insurance death benefit											675	789
Other										594	895	293
Total other noninterest income										11,572	14,055	18,869
Total noninterest income	$ 7,353	$ 9,127	$ 10,131	$ 10,218	$ 10,011	$ 9,127	$ 10,577	$ 8,265	$ 8,029	$ 36,829	$ 37,980	$ 42,813