Covered Loans - Summary of FDIC Loss Sharing Asset (Detail) (USD $) In Thousands, unless otherwise specified					9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2013 Adjustments not Reflected in Income [Member]	Sep. 30, 2012 Adjustments not Reflected in Income [Member]	Sep. 30, 2013 Adjustments Reflected in Income [Member]	Sep. 30, 2012 Adjustments Reflected in Income [Member]
Covered Loans [Line Items]
Beginning balance	$ 91,558	$ 116,624	$ 127,799	$ 168,881
Established through acquisitions
(Amortization) accretion							(6,814)	(10,805)
Cash received from FDIC					(19,415)	(38,736)
Impairment							115	187
Loan expenses to be reimbursed					1,469	2,437
Write-downs/sale of other real estate							1,965	7,854
Recovery amounts due to FDIC							(1,243)	(1,914)
Other					(1,204)	(665)	61	560
Ending balance	$ 91,558	$ 116,624	$ 127,799	$ 168,881