Covered Assets and Indemnification Asset (Details 7) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Changes in the allowance for loan losses
Balance, beginning of period	$ 37,041,000
Provision charged to (recapture from) operations operations	2,687,000	3,242,000
Balance, end of period	39,365,000
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans	4,834,687,000		3,920,476,000
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans	39,365,000
Activity in covered OREO
Balance, beginning of period	136,945,000	142,833,000
Additions to covered OREO	24,042,000	23,190,000
Dispositions of covered OREO	(22,334,000)	(13,282,000)
aluation adjustments in the period	(950,000)	(431,000)
Balance, end of period	137,703,000	152,310,000
Activity in the FDIC Indemnification Asset
Balance, beginning of period	130,437,000	188,291,000
FDIC Indemnification Asset accretion (amortization)	506,000	1,357,000
Transfers to due from FDIC and other	(23,376,000)	(912,000)
Balance, end of period	107,567,000	188,736,000
FDIC, collections received	83,800,000
Covered
Changes in the allowance for loan losses
Balance, beginning of period	4,611,000	1,061,000
Provision charged to (recapture from) operations operations	(107,000)	1,854,000
Loans charged off	(3,116,000)	(250,000)
Balance, end of period	1,388,000	2,665,000
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	1,311,000		801,000
Loans collectively evaluated for impairment	190,608,000		206,451,000
Total loans	552,014,000		642,640,000
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	72,000		77,000
Total loans	1,388,000	2,665,000
Covered | Commercial and industrial
Changes in the allowance for loan losses
Balance, beginning of period	1,193,000	1,053,000
Provision charged to (recapture from) operations operations	71,000	(30,000)
Loans charged off	(900,000)	(91,000)
Balance, end of period	364,000	932,000
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	510,000
Loans collectively evaluated for impairment	5,259,000		10,345,000
Total loans	22,349,000		30,780,000
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	40,000		46,000
Total loans	364,000	932,000
Covered | Real estate
Changes in the allowance for loan losses
Balance, beginning of period	3,334,000	8,000
Provision charged to (recapture from) operations operations	(192,000)	1,732,000
Loans charged off	(2,215,000)	(44,000)
Balance, end of period	927,000	1,696,000
Loan portfolio distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	173,866,000		183,886,000
Total loans	478,040,000		552,850,000
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	20,000		16,000
Total loans	927,000	1,696,000
Covered | Construction and land development
Changes in the allowance for loan losses
Balance, beginning of period	84,000
Provision charged to (recapture from) operations operations	14,000	152,000
Loans charged off	(1,000)	(115,000)
Balance, end of period	97,000	37,000
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	801,000		801,000
Loans collectively evaluated for impairment	11,483,000		12,220,000
Total loans	51,625,000		59,010,000
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	12,000		15,000
Total loans	97,000	37,000
Covered | PCI loans
Changes in the allowance for loan losses
Balance, beginning of period			4,534,000
Balance, end of period	1,316,000		4,534,000
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans	360,095,000		435,388,000
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans	1,316,000		4,534,000
Covered | PCI loans | Commercial and industrial
Changes in the allowance for loan losses
Balance, beginning of period			1,147,000
Balance, end of period	324,000		1,147,000
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans	16,580,000		20,435,000
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans	324,000		1,147,000
Covered | PCI loans | Real estate
Changes in the allowance for loan losses
Balance, beginning of period			3,318,000
Balance, end of period	907,000		3,318,000
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans	304,174,000		368,964,000
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans	907,000		3,318,000
Covered | PCI loans | Construction and land development
Changes in the allowance for loan losses
Balance, beginning of period			69,000
Balance, end of period	85,000		69,000
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans	39,341,000		45,989,000
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans	$ 85,000		$ 69,000