CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities:
Net income	$ 116,433	$ 100,864	$ 53,209
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	13,398	12,516	7,976
Provision for loan losses	4,684	9,023	2,977
Share based compensation expense	3,042	2,645	2,164
Deferred income tax expense	1,719	5,655	6,089
Origination of loans held for sale	(887,216)	(416,337)	(142,877)
Proceeds from sales of loans held for sale	869,294	441,023	149,367
Gains on sales of loans held for sale	(13,006)	(11,699)	(3,403)
(Gains) losses on sales of other real estate owned	173	200	(68)
Investment securities gains	(77)	(190)	(1,273)
Loss on sales of premises and equipment	269	0	0
Tax benefits associated with share based compensation	92	299	1,809
Increase (Decrease) in Operating Capital [Abstract]
Net (increase) decrease in accrued interest receivable	1,327	(2,622)	(891)
Net decrease (increase) in other assets	(3,664)	5,020	(9,829)
Net decrease in accrued expenses and other liabilities	(5,804)	(2,721)	(1,007)
Other - net	(721)	3,970	5,174
Net cash provided by operating activities	99,943	147,646	69,417
Investing activities:
(Purchases) of other equity securities		(8,784)
Proceeds from other equity securities	21,586		576
Purchases of investments available-for-sale	(326,604)	(161,349)	(125,028)
Proceeds from sales of investment available-for-sale	2,926	117,354	2,251
Proceeds from maturities, calls and principal payments of investments available-for-sale	199,652	106,114	123,762
Net increase in loans	(134,012)	(641,521)	(427,773)
Proceeds from the sales of other real estate owned	324	1,151	1,275
Proceeds from sale of loans held for investment	0	59,945	40,031
Acquisition of business activity, net of cash acquired	0	32,487	0
Expenditures for premises and equipment	(5,148)	(10,401)	(7,441)
Net cash used in investing activities	(241,276)	(505,004)	(392,347)
Financing activities:
Net increase in deposits	525,439	340,376	386,118
Net increase/(decrease) in retail repurchase agreements and federal funds purchased	(113,824)	201,184	(5,760)
Proceeds from advances from borrowings	2,298,000	5,477,000	3,965,000
Repayment of advances from borrowings	(2,457,834)	(5,633,579)	(3,989,167)
Retirement of subordinated debt	0	0	(30,000)
Proceeds from issuance of common stock	1,433	1,395	1,200
Stock tendered for payment of withholding taxes	(703)	(760)	(952)
Repurchase of common stock	(24,284)	0	0
Dividends paid	(42,272)	(39,277)	(25,134)
Net cash provided by financing activities	185,955	346,339	301,305
Net increase (decrease) in cash and cash equivalents	44,622	(11,019)	(21,625)
Cash and cash equivalents at beginning of period	101,481	112,500	134,125
Cash and cash equivalents at end of period	146,103	101,481	112,500
Supplemental Disclosures:
Interest payments	84,448	60,504	26,377
Income tax payments	33,795	25,664	31,738
Transfer from loans to residential mortgage loans held for sale	0	60,043	39,744
Transfers from loans to other real estate owned	$ 414	$ 289	$ 1,588