Loss Sharing Agreements and FDIC Loss Share Receivable - Schedule of FDIC Loss Share Receivables (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
FDIC Indemnification Asset [Roll Forward]
Balance at beginning of period			$ 69,627	$ 162,312
Change due to (reversal of) loan loss provision recorded on FDIC covered loans			(1,342)	1,153
Amortization	$ (5,600)	$ (25,120)	(19,011)	(61,393)
(Submission of reimbursable losses) recoveries payable to the FDIC			(4,084)	4,901
Impairment			0	(5,097)
Changes due to a change in cash flow assumptions on OREO and other changes			(1,747)	(7,164)
Balance at end of period	$ 43,443	$ 94,712	$ 43,443	$ 94,712