Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES
Net income	$ 215,713	$ 92,940	$ 96,814
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	28,412	21,062	16,978
Provision for loan losses	38,148	26,393	20,065
Gain on sale of investments	(61)	(1,059)	(5,848)
Net accretion of investment securities and assets	(48,684)	(38,090)	(31,928)
Net (accretion) amortization on borrowings	(380)	561	421
Stock-based compensation expense	9,725	10,681	3,418
Gain on sale of premises and equipment held for sale, net of impairment	0	(615)	(225)
Gain on sale of foreclosed assets and other real estate owned	(650)	(1,076)	(2,432)
Gain on sale of mortgage loans held for sale	(12,844)	(12,186)	(14,683)
Gain on sale of loans	(10)	(18)	0
Fair value write-down of closed branches	836	325	3,000
Deferred income taxes	8,412	23,251	9,832
Gain on sale of insurance lines of business	0	(3,708)	0
Income from bank owned life insurance	(5,003)	(3,503)	(3,372)
Originations of mortgage loans held for sale	(546,676)	(507,907)	(618,453)
Proceeds from sale of mortgage loans held for sale	556,759	526,245	635,613
Changes in assets and liabilities:
Interest receivable	(6,227)	(2,432)	(1,197)
Assets held in trading accounts	0	41	4,381
Other assets	(1,414)	12,456	(8,206)
Accrued interest and other liabilities	33,978	(14,194)	(14,959)
Income taxes payable	(9,355)	(14,604)	1,915
Net cash provided by operating activities	260,679	114,563	91,134
INVESTING ACTIVITIES
Net originations of loans	(912,793)	(719,219)	(368,162)
Proceeds from sale of loans	24,977	20,705	0
(Increase) decrease in due from banks - time	(1,620)	3,233	9,544
Purchases of premises and equipment, net	(29,740)	(34,216)	(18,892)
Proceeds from sale of premises and equipment	0	3,475	1,628
Purchases of other real estate owned	0	(1,021)	0
Proceeds from sale of foreclosed assets and other real estate owned	27,751	18,255	29,055
Proceeds from sale of available-for-sale securities	7,959	679,613	346,273
Proceeds from maturities of available-for-sale securities	258,325	487,717	257,388
Purchases of available-for-sale securities	(825,914)	(854,708)	(861,572)
Proceeds from maturities of held-to-maturity securities	80,803	97,494	250,636
Purchases of held-to-maturity securities	(1,172)	(860)	(6,162)
Proceeds from bank owned life insurance death benefits	1,814	0	3,039
Purchases of bank owned life insurance	(4,000)	(143)	(143)
Proceeds from the sale of insurance lines of business	0	9,296	0
Cash paid in business combinations, net of cash received	0	(48,092)	0
Cash received in business combinations, net of cash paid	0	0	106,419
Disposition of assets and liabilities held for sale	(55,211)	0	0
Net cash used in investing activities	(1,428,821)	(338,471)	(250,949)
FINANCING ACTIVITIES
Net change in deposits	1,305,877	120,667	139,266
Proceeds from issuance of subordinated notes	326,355	0	0
Repayments of subordinated debentures and subordinated debt	(113,990)	(3,000)	(594)
Dividends paid on preferred stock	0	0	(24)
Dividends paid on common stock	(55,646)	(35,116)	(28,743)
Net change in other borrowed funds	(34,574)	521,865	106,823
Net change in federal funds purchased and securities sold under agreements to repurchase	(26,652)	(71,003)	2,398
Net shares issued under stock compensation plans	1,162	2,260	4,352
Shares issued under employee stock purchase plan	1,026	618	586
Redemption of preferred stock	0	0	(30,852)
Net cash provided by financing activities	1,403,558	536,291	193,212
INCREASE IN CASH EQUIVALENTS	235,416	312,383	33,397
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	598,042	285,659	252,262
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 833,458	$ 598,042	$ 285,659