CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - UNAUDITED - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Operating activities:
Net income	$ 30,317	$ 21,665
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,326	2,990
Provision for loan losses	(128)	1,997	$ 9,023
Stock based compensation expense	690	582
Tax benefits associated with share based compensation	41	34
Deferred Income Tax Expense (Benefit)	1,069	(1,673)
Origination of loans held for sale	(97,286)	(47,975)
Proceeds from sales of loans held for sale	97,456	58,121
(Gains)/ losses on sales of loans held for sale	(2,395)	(2,872)
(Gains) losses on sales of other real estate owned	0	90
Investment securities gains	0	(63)
Increase (Decrease) in Operating Capital [Abstract]
Net (increase) decrease in accrued interest receivable	(1,573)	(397)
Net decrease (increase) in other assets	5,191	11,407
Net increase (decrease) in accrued expenses and other liabilities	(10,381)	(403)
Other - net	992	754
Net cash provided by operating activities	27,319	44,257
Investing activities:
(Purchases) of other equity securities		(700)
Proceeds from other equity securities	12,620
Purchases of investments available-for-sale	(15,919)	(497)
Proceeds from sales of investment available-for-sale	0	994
Proceeds from maturities, calls and principal payments of investments available-for-sale	34,829	23,975
Net (increase)/ decrease in loans	1,644	(123,945)
Proceeds from the sales of other real estate owned	0	292
Proceeds from sales of loans previously held for investment	0	59,945
Acquisition of business activity, net of cash paid	0	32,552
Expenditures for premises and equipment	(1,066)	(2,842)
Net cash provided/ (used) by investing activities	32,108	(10,226)
Financing activities:
Net increase in deposits	309,643	52,702
Net increase/(decrease) in retail repurchase agreements and federal funds purchased	(204,803)	23,078
Proceeds from advances from FHLB	1,079,000	1,990,000
Repayment of advances from FHLB	(1,201,333)	(1,984,081)
Proceeds from issuance of common stock	343	456
Stock tendered for payment of withholding taxes	(101)	0
Dividends paid	(10,008)	(9,267)
Net cash used by financing activities	(27,259)	72,888
Net increase (decrease) in cash and cash equivalents	32,168	106,919
Cash and cash equivalents at beginning of period	101,481	112,500	112,500
Cash and cash equivalents at end of period	133,649	219,419	$ 101,481
Supplemental Disclosures:
Interest payments	21,455	11,680
Income tax payments	0	15
Transfer from loans to residential mortgage loans held for sale	0	60,043
Transfers from loans to other real estate owned	$ 0	$ 289