Business Combinations (Summary of FDIC Indemnification Asset) (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	$ 3,429	$ 46,115	$ 11,846	$ 85,672
Additions from acquisitions	0	0	0	0
Additions from reimbursable expenses	1,039	1,584	3,548	4,933
Amortization	(718)	(1,382)	(3,184)	(4,441)
Changes in expected reimbursements from the FDIC for changes in expected credit losses	(5,236)	(12,124)	(13,546)	(41,153)
Payments received from the FDIC	(1,547)	(6,834)	(1,697)	(17,652)
Balance at end of period	0	$ 27,359	0	$ 27,359
Other Liabilities
FDIC Indemnification Asset [Roll Forward]
Balance at end of period	$ (3,033)		$ (3,033)