Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 116,998	$ 75,272	$ 80,349
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	30,791	30,144	30,757
Provision for loan losses	24,013	15,563	11,694
Net amortization of premium on securities	25,142	26,961	32,101
Provision for deferred taxes	2,760	13,263	7,162
Securities gains, net	(1,085)	(6,973)	(11,340)
Unrealized gain on equity securities, net	212	0	0
Stock based compensation	4,505	4,068	3,478
Loss on sales/valuations of assets, net	2,208	2,475	1,478
Loans originated for sale	(646,019)	(728,681)	(1,119,817)
Proceeds on sales of loans held for sale	714,259	760,484	1,160,079
Net gains on sales of loans held for sale	(16,404)	(15,102)	(26,740)
Increase in accrued interest receivable	(3,368)	(593)	(779)
Decrease in prepaid expenses	2,364	576	194
Increase (decrease) in accrued interest payable	(2)	34	(835)
Gain on extinguishment of debt	0	(1,280)	0
Capitalization of servicing rights	(5,160)	(7,358)	(12,894)
Valuation adjustment on servicing rights	46	(21)	33
Net excess tax benefit from stock based compensation	674	1,246	374
Other, net	(8,760)	(14,148)	(6,769)
NET CASH PROVIDED BY OPERATING ACTIVITIES	242,750	155,930	148,525
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of time deposits in other financial institutions	(1,000)	0	0
Proceeds from the sale of securities available for sale	727,895	1,456,750	909,942
Proceeds from the sale of securities held to maturity	0	0	4,557
Proceeds from the redemption of time deposits in other financial institutions	8,767	12,171	0
Proceeds from the maturity of and principal paydowns on securities available for sale	237,747	222,656	188,071
Proceeds from the maturity of and principal paydowns on securities held to maturity	15,953	10,621	9,683
Proceeds from the maturity of and principal paydowns on time deposits in other financial institutions	6,993	34,904	250
Proceeds from the maturity of and principal paydowns on time deposits in other financial institutions	1,618	2,790	5,673
Purchase of securities available for sale	(1,197,822)	(1,816,564)	(1,335,244)
Purchase of other investments	(3,731)	(1,116)	(2,250)
Net (increase) decrease in loans	(132,401)	22,109	222,874
Purchase of bank owned life insurance policies	(2,228)	(2,000)	0
Proceeds from bank owned life insurance policies	0	0	111
Proceeds from sale of mortgage servicing rights	0	6,290	0
Capital expenditures	(12,742)	(8,113)	(10,327)
Net cash and cash equivalents received in acquisitions	212,197	71,089	8,084
Proceeds from sale of equipment	2,972	4,867	947
Proceeds on sale of OREO and other repossessed assets	11,562	10,844	4,484
NET CASH PROVIDED (USED) BY INVESTING ACTIVITIES	(124,220)	27,298	6,855
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in demand deposits	8,052	154,394	123,613
Net increase (decrease) in savings accounts	318,697	(166,733)	86,319
Net decrease in time deposit accounts	(221,980)	(79,733)	(416,455)
Proceeds on short-term revolving credit line	25,000	20,000	0
Repayments on short-term revolving credit line	(25,000)	(20,000)	0
Net decrease in short-term borrowings	(158,519)	(25,847)	(15,921)
Proceeds from short term FHLB advances	462,940	251,139	329,566
Repayments of short term FHLB advances	(402,102)	(241,505)	(336,850)
Proceeds from other borrowings	30,131	0	40,000
Repayments of other borrowings	(59,157)	(9,645)	(21,636)
Redemption of preferred stock	0	0	(81,698)
Payment for the redemption of debt	0	(13,800)	0
Purchase of treasury stock	(97)	(625)	(3,719)
Proceeds from issuance of common stock	489	963	54,196
Dividends paid	(19,357)	(14,557)	(12,870)
NET CASH USED BY FINANCING ACTIVITIES	(40,903)	(145,949)	(255,455)
Net increase (decrease) in cash and cash equivalents	77,627	37,279	(100,075)
Cash and cash equivalents at beginning of year	196,003	158,724	258,799
CASH AND CASH EQUIVALENTS AT END OF PERIOD	273,630	196,003	158,724
Supplemental disclosures:
Cash paid for income/franchise taxes	17,085	15,817	24,652
Cash paid for interest	51,868	33,316	32,648
Loans transferred to OREO	7,866	5,293	2,315
Transfer of premises from premises, furniture and equipment held for sale to premises, furniture and equipment, net	81	2,372	3,440
Purchases of securities available for sale, accrued, not paid	0	1,017	0
Transfer of premises from premises, furniture and equipment, net to premises, furniture and equipment held for sale	7,660	3,442	0
Sales of securities available for sale, accrued, not settled	0	0	250
Conversion of convertible debt to common stock	0	558	1,442
Conversion/redemption of Series D preferred stock to common stock	938	419	2,420
Loans transferred to held for sale	96,027	0	0
Deposits transferred to held for sale	106,409	0	0
Stock consideration granted for acquisitions	$ 238,075	$ 175,196	$ 57,433