Other Real Estate Owned (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Other Real Estate Owned Rollforward [Line Items]
Other Real Estate Owned Beginning Balance	$ 241,727,000	$ 295,712,000	$ 265,766,000	$ 303,508,000
Other Real Estate Owned Write Downs	(18,973,000)	(8,585,000)	(36,909,000)	(14,238,000)
Other Real Estate Owned Additions	35,827,000	48,066,000	68,356,000	85,302,000
Other Real Estate Owned Sales	(83,202,000)	(36,144,000)	(121,001,000)	(73,967,000)
Othe Real Estate Owned Other Adjustments	380,000	(3,824,000)	(453,000)	(5,380,000)
Reclassification Of Other Real Estate Expiration LSA	0		0
Other Real Estate Owned Ending Balance	175,759,000	295,225,000	175,759,000	295,225,000
Non Covered Under Loss Sharing Agreements With F D I C [Member] | Mortgages [Member]
Other Real Estate Owned Rollforward [Line Items]
Other Real Estate Owned Beginning Balance	102,562,000	88,824,000	96,517,000	86,852,000
Other Real Estate Owned Write Downs	(2,463,000)	(439,000)	(3,835,000)	(1,108,000)
Other Real Estate Owned Additions	18,532,000	15,400,000	39,607,000	30,283,000
Other Real Estate Owned Sales	(14,243,000)	(12,203,000)	(27,329,000)	(24,266,000)
Othe Real Estate Owned Other Adjustments	50,000	(1,949,000)	(522,000)	(2,128,000)
Reclassification Of Other Real Estate Expiration LSA	3,092,000		3,092,000
Other Real Estate Owned Ending Balance	107,530,000	89,633,000	107,530,000	89,633,000
Non Covered Under Loss Sharing Agreements With F D I C [Member] | Commercial Or Construction [Member]
Other Real Estate Owned Rollforward [Line Items]
Other Real Estate Owned Beginning Balance	25,608,000	48,141,000	38,983,000	48,649,000
Other Real Estate Owned Write Downs	(4,162,000)	(571,000)	(10,049,000)	(785,000)
Other Real Estate Owned Additions	2,793,000	6,303,000	4,828,000	10,971,000
Other Real Estate Owned Sales	(4,868,000)	(5,372,000)	(14,295,000)	(10,334,000)
Othe Real Estate Owned Other Adjustments	850,000	1,286,000	754,000	1,286,000
Reclassification Of Other Real Estate Expiration LSA	14,504,000		14,504,000
Other Real Estate Owned Ending Balance	34,725,000	49,787,000	34,725,000	49,787,000
Covered Under Loss Sharing Agreements With F D I C [Member] | Mortgages [Member]
Other Real Estate Owned Rollforward [Line Items]
Other Real Estate Owned Beginning Balance	42,984,000	48,414,000	44,872,000	47,792,000
Other Real Estate Owned Write Downs	(1,393,000)	(940,000)	(2,675,000)	(1,147,000)
Other Real Estate Owned Additions	8,879,000	4,103,000	14,260,000	8,594,000
Other Real Estate Owned Sales	(13,806,000)	(3,777,000)	(19,628,000)	(6,154,000)
Othe Real Estate Owned Other Adjustments	(68,000)	100,000	(233,000)	(1,185,000)
Reclassification Of Other Real Estate Expiration LSA	(3,092,000)		(3,092,000)
Other Real Estate Owned Ending Balance	33,504,000	47,900,000	33,504,000	47,900,000
Covered Under Loss Sharing Agreements With F D I C [Member] | Commercial Or Construction [Member]
Other Real Estate Owned Rollforward [Line Items]
Other Real Estate Owned Beginning Balance	70,573,000	110,333,000	85,394,000	120,215,000
Other Real Estate Owned Write Downs	(10,955,000)	(6,635,000)	(20,350,000)	(11,198,000)
Other Real Estate Owned Additions	5,623,000	22,260,000	9,661,000	35,454,000
Other Real Estate Owned Sales	(50,285,000)	(14,792,000)	(59,749,000)	(33,213,000)
Othe Real Estate Owned Other Adjustments	(452,000)	(3,261,000)	(452,000)	(3,353,000)
Reclassification Of Other Real Estate Expiration LSA	(14,504,000)		(14,504,000)
Other Real Estate Owned Ending Balance	$ 0	$ 107,905,000	$ 0	$ 107,905,000