Other Real Estate Owned (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
OREO activity
Balance, beginning of year	$ 23,496,000	$ 38,092,000
Additions	1,085,000	2,033,000
Sales	(5,410,000)	(5,690,000)
Valuation adjustments	(1,662,000)	(168,000)
Balance, end of year	17,509,000	34,267,000
OREO Valuation Allowances	4,100,000		7,400,000
Non-Covered OREO
OREO activity
Balance, beginning of year	10,736,000	12,611,000
Sales	(4,779,000)	(3,186,000)
Valuation adjustments		(13,000)
Balance, end of year	5,957,000	9,412,000
Residential mortgage loans in process of foreclosure	6,900,000
Covered OREO
OREO activity
Balance, beginning of year	12,760,000	25,481,000
Additions	1,085,000	2,033,000
Sales	(631,000)	(2,504,000)
Valuation adjustments	(1,662,000)	(155,000)
Balance, end of year	$ 11,552,000	$ 24,855,000
FDIC reimbursement (as a percent)	80.00%
Payable to FDIC (as a percent)	80.00%