Other Noninterest Expense - Components of Other Noninterest Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]
Advertising	$ 2,179	$ 2,181	$ 3,938	$ 4,358
Ad valorem and franchise taxes	2,638	2,182	5,299	4,384
Printing and supplies	949	1,511	2,278	2,820
Insurance expense	1,018	1,065	2,058	2,131
Travel expense	1,061	1,288	1,957	2,401
Entertainment and contributions	1,529	1,269	2,941	2,991
Tax credit investment amortization	2,198	1,247	4,370	2,673
Other miscellaneous	13,736	5,037	18,284	12,653
Total other noninterest expense	$ 25,308	$ 15,780	$ 41,125	$ 34,411