Loans and Allowance for Loan Losses - Schedule of Activity in Loss Share Receivable (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Receivables [Abstract]
Balance, January 1			$ 113,834	$ 177,844
Amortization	(2,760)	(590)	(9,989)	(590)
Charge-offs, write-downs and other losses (recoveries)			(793)	(190)
External expenses qualifying under loss share agreement			3,325	7,918
Changes due to changes in cash flow projections			(14,569)
Settlement of disallowed loss claims			(10,268)
Net payments (to) from FDIC			366	(60,886)
Ending balance	$ 81,906	$ 124,096	$ 81,906	$ 124,096