CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 137,938	$ 149,129	$ 116,998
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	27,289	30,797	30,791
Provision for credit losses	67,066	16,657	24,013
Net amortization of premium on securities	16,042	20,326	25,142
Provision for deferred taxes	(10,910)	(414)	2,760
Securities gains, net	(7,793)	(7,659)	(1,085)
Unrealized gain on equity securities, net	(640)	(525)	(212)
Stock based compensation	7,410	6,070	4,505
(Gain) loss on sales/valuations of assets, net	5,101	(8,394)	2,208
Loans originated for sale	(621,507)	(384,603)	(646,019)
Proceeds on sales of loans held for sale	615,439	396,290	714,259
Net gains on sales of loans held for sale	(25,133)	(14,661)	(16,404)
(Increase) decrease in accrued interest receivable	(9,971)	1,301	(3,368)
(Increase) decrease in prepaid expenses	(3,504)	(8,566)	2,364
Increase (decrease) in accrued interest payable	(2,915)	421	(2)
Gain on extinguishment of debt	0	(375)	0
Capitalization of servicing rights	(3,484)	(1,011)	(5,160)
Valuation adjustment on servicing rights	1,778	911	46
Excess tax (expense) benefit from stock based compensation	(93)	266	674
Other, net	(1,745)	(34,786)	(8,760)
NET CASH PROVIDED BY OPERATING ACTIVITIES	190,368	161,174	242,750
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of time deposits in other financial institutions	0	(258)	(1,000)
Proceeds from the sale of securities available for sale	1,097,378	1,628,467	727,895
Proceeds from the sale of securities held to maturity	1,056	0	0
Proceeds from the sale, maturity of and principal paydowns on other investments	8,506	10,325	1,618
Proceeds from the redemption of time deposits in other financial institutions	0	0	8,767
Proceeds from the maturity of and principal paydowns on securities available for sale	567,884	402,946	237,747
Proceeds from the maturity of and principal paydowns on securities held to maturity	3,458	3,158	15,953
Proceeds from the maturity of time deposits in other financial institutions	585	1,216	6,993
Purchase of securities available for sale	(4,119,814)	(2,577,106)	(1,197,822)
Purchase of other investments	(49,228)	(6,446)	(3,731)
Net increase in loans	(444,146)	(90,749)	(132,401)
Purchase of bank owned life insurance policies	(292)	(28)	(2,228)
Proceeds from bank owned life insurance policies	606	1,402	0
Proceeds from sale of mortgage servicing rights	0	35,017	0
Capital expenditures and investments	(18,542)	(17,928)	(12,742)
Net cash and cash equivalents received in acquisitions	641,315	76,071	212,197
Net cash expended in divestitures	0	(49,264)	0
Proceeds from sale of equipment	5,895	903	2,972
Proceeds on sale of OREO and other repossessed assets	3,913	8,304	11,562
NET CASH USED BY INVESTING ACTIVITIES	(2,301,426)	(573,970)	(124,220)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in demand deposits	1,367,903	51,178	8,052
Net increase in savings accounts	735,968	680,641	318,697
Net decrease in time deposit accounts	(254,540)	(81,251)	(221,980)
Proceeds on short-term revolving credit line	0	0	25,000
Repayments on short-term revolving credit line	0	0	(25,000)
Net increase (decrease) in short-term borrowings	40,137
Net increase (decrease) in short-term borrowings		(51,314)	(158,519)
Proceeds from short term FHLB advances	516,545	512,085	462,940
Repayments of short term FHLB advances	(597,742)	(546,725)	(402,102)
Proceeds from other borrowings	314,397	50	30,131
Repayments of other borrowings	(134,244)	(20,693)	(59,157)
Proceeds from issuance of preferred stock	110,705	0	0
Payment for the redemption of debt	0	(2,125)	0
Purchase of treasury stock	0	0	(97)
Proceeds from issuance of common stock	3,004	661	489
Dividends paid	(31,906)	(24,607)	(19,357)
NET CASH PROVIDED (USED) BY FINANCING ACTIVITIES	2,070,227	517,900	(40,903)
Net increase (decrease) in cash and cash equivalents	(40,831)	105,104	77,627
Cash and cash equivalents at beginning of year	378,734	273,630	196,003
CASH AND CASH EQUIVALENTS AT END OF PERIOD	337,903	378,734	273,630
Supplemental disclosures:
Cash paid for income/franchise taxes	33,402	37,609	17,085
Cash paid for interest	47,798	80,238	51,868
Loans transferred to OREO	3,511	8,066	7,866
Transfer of premises from premises, furniture and equipment held for sale to premises, furniture and equipment, net	855	4,306	81
Purchases of securities available for sale, accrued, not paid	0	11,106	0
Transfer of premises from premises, furniture and equipment, net to premises, furniture and equipment held for sale	8,134	4,655	7,660
Securities transferred from held to maturity to available for sale	0	148,030	0
Conversion/redemption of Series D preferred stock to common stock	0	0	938
Securities transferred from available for sale to held to maturity	462	0	0
Loans transferred to held for sale	0	32,111	96,027
Deposits transferred to held for sale	0	76,968	106,409
Dividends declared, not paid	2,013	0	0
Stock consideration granted for acquisitions	$ 217,202	$ 92,258	$ 238,075