Other Noninterest Expense - Components of Other Noninterest Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]
Insurance expense	$ 887	$ 1,207	$ 3,018	$ 4,428
Ad valorem and franchise taxes	2,809	2,185	7,193	6,608
Printing and supplies	1,143	1,488	3,963	6,162
Public relations and contributions	969	1,065	3,960	4,827
Travel expense	1,074	1,282	3,475	4,464
Other real estate owned expense, net	2,439	4,590	6,502	11,630
Tax credit investment amortization	4,880	1,513	7,553	4,538
Other miscellaneous	19,851	4,488	32,504	19,311
Total other noninterest expense	$ 34,052	$ 17,818	$ 68,168	$ 61,968