Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
OPERATING ACTIVITIES
Net income	$ 35,688,000	$ 23,231,000	$ 27,684,000
Items not requiring (providing) cash:
Depreciation and amortization	7,933,000	6,127,000	5,516,000
Provision for loan losses	7,245,000	4,118,000	4,140,000
(Gain) loss on sale of investment securities	(8,000)	151,000	(2,000)
Net accretion of investment securities and assets not covered by FDIC loss share	(8,711,000)	(1,233,000)	(283,000)
Stock-based compensation expense	1,423,000	1,417,000	1,388,000
Net accretion on assets covered by FDIC loss share	(1,497,000)	(5,878,000)	(2,807,000)
Gain on FDIC-assisted transactions			(3,411,000)
Gain on sale of premises and equipment, net of impairment	(4,630,000)
Deferred income taxes	(9,029,000)	(4,618,000)	485,000
Bank owned life insurance income	(1,843,000)	(1,319,000)	(1,463,000)
Changes in:
Interest receivable	359,000	(1,097,000)	596,000
Mortgage loans held for sale	(11,771,000)	15,873,000	(2,391,000)
Assets held in trading accounts	1,991,000	(2,754,000)	1,317,000
Other assets	(17,313,000)	6,047,000	1,961,000
Accrued interest and other liabilities	6,511,000	(3,032,000)	3,054,000
Income taxes payable	5,272,000	(944,000)	298,000
Net cash provided by operating activities	11,620,000	36,089,000	36,082,000
INVESTING ACTIVITIES
Net (originations) collections of loans	(83,825,000)	(90,977,000)	(48,502,000)
Net collections of loans covered by FDIC loss share	55,361,000	78,305,000	83,460,000
Proceeds from sale of student loans	22,136,000
Proceeds from sale of premises held for sale	30,055,000
Purchases of premises and equipment, net	(11,293,000)	(4,772,000)	(2,268,000)
Proceeds from sale of foreclosed assets held for sale	26,900,000	18,832,000	8,322,000
Proceeds from sale of foreclosed assets held for sale, covered by FDIC loss share	14,328,000	16,274,000	14,560,000
Proceeds from sale of available-for-sale securities	20,609,000	44,662,000	2,576,000
Proceeds from maturities of available-for-sale securities	194,423,000	165,606,000	347,205,000
Purchases of available-for-sale securities	(265,835,000)	(89,986,000)	(336,924,000)
Proceeds from maturities of held-to-maturity securities	403,186,000	112,359,000	713,362,000
Purchases of held-to-maturity securities	(413,020,000)	(273,924,000)	(683,820,000)
Purchases of bank owned life insurance	(7,826,000)	(7,000,000)	(25,000)
Net cash proceeds received in FDIC-assisted transactions			76,586,000
Cash received on FDIC loss share	15,700,000	14,530,000	12,471,000
Purchases of credit card loans		(10,999,000)
Cash paid in business combinations, net of cash received	11,343,000	35,485,000
Net cash provided by investing activities	12,242,000	8,395,000	187,003,000
FINANCING ACTIVITIES
Net change in deposits	(192,211,000)	(14,103,000)	(173,379,000)
Dividends paid	(15,359,000)	(13,707,000)	(13,495,000)
Net change in other borrowed funds	(13,385,000)	(8,988,000)	(8,922,000)
Repayment of subordinated debentures			(10,310,000)
Net change in fed funds purchased and securities sold under agreements to repurchase	(8,401,000)	3,809,000	(32,144,000)
Net shares issued under stock compensation plans	2,023,000	936,000	323,000
Repurchase of common stock		(10,848,000)	(17,567,000)
Net cash used in financing activities	(227,333,000)	(42,901,000)	(255,494,000)
(DECREASE) INCREASE IN CASH EQUIVALENTS	(203,471,000)	1,583,000	(32,409,000)
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	539,380,000	537,797,000	570,206,000
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 335,909,000	$ 539,380,000	$ 537,797,000