Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
OPERATING ACTIVITIES
Net income	$ 74,037,000	$ 69,843,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	14,589,000	12,229,000
Provision for loan losses	16,792,000	15,733,000
Gain on sale of investments	(2,302,000)	(4,403,000)
Net accretion of investment securities and assets	(19,472,000)	(22,863,000)
Net amortization on borrowings	319,000	314,000
Stock-based compensation expense	5,675,000	2,679,000
Gain on sale of premises and equipment, net of impairment	(615,000)	(159,000)
Gain on sale of foreclosed assets and other real estate owned	(801,000)	(1,731,000)
Gain on sale of mortgage loans held for sale	(8,809,000)	(11,150,000)
Fair value write-down of closed branches	325,000	3,000,000
Deferred income taxes	4,962,000	1,070,000
Increase in cash surrender value of bank owned life insurance	(2,402,000)	(2,429,000)
Originations of mortgage loans held for sale	(353,714,000)	(472,902,000)
Proceeds from sale of mortgage loans held for sale	377,697,000	486,248,000
Changes in assets and liabilities:
Interest receivable	(1,129,000)	(799,000)
Assets held in trading accounts	(8,000)	1,453,000
Other assets	8,249,000	16,680,000
Accrued interest and other liabilities	(9,738,000)	(13,950,000)
Income taxes payable	4,819,000	(2,286,000)
Net cash provided by operating activities	108,474,000	76,577,000
INVESTING ACTIVITIES
Net originations of loans	(427,789,000)	(140,240,000)
Decrease in due from banks - time	2,488,000	9,714,000
Purchases of premises and equipment, net	(28,971,000)	(8,840,000)
Proceeds from sale of premises and equipment	3,475,000	890,000
Purchases of other real estate owned	(1,021,000)
Proceeds from sale of foreclosed assets and other real estate owned	11,401,000	24,095,000
Proceeds from sale of available-for-sale securities	327,218,000	249,079,000
Proceeds from maturities of available-for-sale securities	76,615,000	137,832,000
Purchases of available-for-sale securities	(380,308,000)	(498,011,000)
Proceeds from maturities of held-to-maturity securities	57,896,000	215,846,000
Purchases of held-to-maturity securities	(860,000)	(6,162,000)
Proceeds from bank owned life insurance death benefits		2,043,000
Purchases of bank owned life insurance	(143,000)	(143,000)
Proceeds from the sale of insurance lines of business	3,707,000
Cash paid in business combinations, net of cash received	(22,000,000)
Cash received in business combinations, net of cash paid		106,419,000
Net cash (used in) provided by investing activities	(378,292,000)	92,522,000
FINANCING ACTIVITIES
Net change in deposits	201,395,000	21,428,000
Repayments of subordinated debentures		(594,000)
Dividends paid on preferred stock		(24,000)
Dividends paid on common stock	(23,986,000)	(21,227,000)
Net change in other borrowed funds	246,382,000	48,940,000
Net change in federal funds purchased and securities sold under agreements to repurchase	(10,505,000)	11,658,000
Net shares issued under stock compensation plans	2,545,000	3,247,000
Shares issued under employee stock purchase plan	618,000	586,000
Redemption of preferred stock		(30,852,000)
Net cash provided by financing activities	416,449,000	33,162,000
INCREASE IN CASH AND CASH EQUIVALENTS	146,631,000	202,261,000
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	285,659,000	252,262,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 432,290,000	$ 454,523,000