CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 34,612	$ 33,710	$ 111,278	$ 84,857
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			23,561	22,647
Provision for loan losses	5,201	5,238	11,754	14,332
Net amortization of premium on securities			15,959	18,958
Securities gains, net	(2,013)	145	(7,168)	(1,037)
Unrealized gain on equity securities, net			(514)	(97)
Stock based compensation			4,833	3,689
Loans originated for sale			(289,877)	(551,328)
Proceeds on sales of loans held for sale			289,769	594,529
Net gains on sale of loans held for sale			(11,545)	(13,939)
(Increase) decrease in accrued interest receivable			932	(5,422)
(Increase) decrease in prepaid expenses			(3,611)	2,243
Increase in accrued interest payable			1,905	1,121
Gain on extinguishment of debt			(375)	0
Capitalization of servicing rights			(756)	(4,404)
Valuation allowance on servicing rights	626	(230)	1,579	(12)
(Gain)/loss on sales/valuations of assets, net			(10,378)	2,243
Net excess tax benefit from stock based compensation			270	672
Other, net			(40,706)	(1,979)
NET CASH PROVIDED BY OPERATING ACTIVITIES			96,910	167,073
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of time deposits in other financial institutions			(254)	(1,000)
Proceeds from the sale of securities available for sale	290,877	59,137	1,485,773	694,872
Proceeds from the redemption of time deposits in other financial institutions			0	8,767
Proceeds from the maturity of and principal paydowns on securities available for sale			265,500	172,702
Proceeds from the maturity of and principal paydowns on securities held to maturity			2,938	13,169
Proceeds from the maturity of and principal paydowns on time deposits in other financial institutions			1,215	5,829
Proceeds from the sale, maturity of and principal paydowns on other investments			10,297	2,038
Purchase of securities available for sale			(1,984,228)	(940,607)
Purchase of other investments			(4,957)	(2,411)
Net increase in loans			(47,023)	(13,737)
Purchase of bank owned life insurance policies			(16)	(2,000)
Proceeds from bank owned life insurance policies			421	0
Proceeds from sale of mortgage servicing rights			33,823	0
Capital expenditures			(8,389)	(11,793)
Net cash and cash equivalents received in acquisitions			38,650	212,197
Proceeds from the sale of equipment			1,277	998
Net cash expended in divestiture			(49,264)	0
Proceeds on sale of OREO and other repossessed assets			6,907	3,128
NET CASH PROVIDED (USED) BY INVESTING ACTIVITIES			(247,330)	142,152
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in demand deposits			159,044	156,497
Net increase in savings deposits			347,749	130,704
Net decrease in time deposit accounts			(397)	(122,795)
Proceeds on short-term revolving credit line			0	25,000
Repayments on short-term revolving credit line			0	(25,000)
Net decrease in short-term borrowings			(43,733)	(183,552)
Proceeds from short term FHLB advances			430,888	355,602
Repayments of short term FHLB advances			(531,725)	(365,602)
Proceeds from other borrowings			50	30,131
Repayments of other borrowings			(17,769)	(56,221)
Payment for the redemption of debt			(2,125)	0
Purchase of treasury stock			0	(97)
Proceeds from issuance of common stock			576	286
Dividends paid			(18,001)	(12,806)
NET CASH PROVIDED (USED) BY FINANCING ACTIVITIES			324,557	(67,853)
Net increase in cash and cash equivalents			174,137	241,372
Cash and cash equivalents at beginning of year			273,630	196,003	$ 196,003
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 447,767	$ 437,375	447,767	437,375	$ 273,630
Supplemental disclosures:
Cash paid for income/franchise taxes			30,523	14,754
Cash paid for interest			58,297	34,725
Loans transferred to OREO			7,421	5,016
Transfer of premises from premises, furniture and equipment, net, to premises, furniture and equipment held for sale			2,568	3,415
Transfer of premises from premises, furniture and equipment held for sale to premises, furniture and equipment, net,			1,564	0
Deposits transferred to held for sale			76,968	50,312
Loans transferred to held for sale			32,111	31,379
Securities transferred from held to maturity to available for sale			148,030	0
Purchases of securities available for sale, accrued, not settled			22,879	3,481
Conversion of Series D preferred stock to common stock			0	938
Stock consideration granted for acquisitions			$ 92,258	$ 238,075