CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
OPERATING ACTIVITIES:
Net income	$ 45,632	$ 45,903	$ 35,166
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization on investment securities, net	245	503	729
Accretion on loans and amortization of core deposit intangible, net	(6,373)	(2,573)	(2,835)
Depreciation of premises and equipment	8,472	7,304	6,610
Amortization of mortgage servicing rights	1,504	1,757	1,400
Provision for loan and lease losses	27,704	14,493	5,396
Net gain on sale of mortgage loans held for sale	(3,977)	(6,656)	(3,915)
Origination of mortgage loans held for sale	(160,091)	(216,812)	(160,989)
Proceeds from sale of mortgage loans held for sale	169,969	214,760	167,209
Net gain on sale of consumer loans held for sale	(5,647)	(2,835)	(978)
Origination of consumer loans held for sale	(663,171)	(380,066)	(137,551)
Proceeds from sale of consumer loans held for sale	661,098	379,907	138,015
Net gain on sale of banking center			(28)
Net realized losses (gains) on sales, calls and impairment of securities	136		(88)
Net gain realized on sale of other real estate owned	(831)	(514)	(956)
Writedowns of other real estate owned	155	270	1,257
Impairment of premises held for sale	1,175	191	132
Deferred director compensation expense - Class A Common Stock	191	170	223
Stock based compensation expense	1,142	1,030	422
Increase in cash surrender value of bank owned life insurance	(1,562)	(1,516)	(1,402)
Net change in other assets and liabilities:
Accrued interest receivable	(1,726)	(659)	(426)
Accrued interest payable	152	(298)	(33)
Other assets	730	(7,227)	(2,785)
Other liabilities	2,850	540	5,473
Net cash provided by operating activities	77,777	47,672	50,046
INVESTING ACTIVITIES:
Net change in cash for acquisition of Cornerstone Bancorp, Inc.		(9,088)
Purchases of securities available for sale	(225,212)	(419,254)	(1,512,809)
Purchases of securities held to maturity	(15,595)	(19,935)
Proceeds from calls, maturities and paydowns of securities available for sale	158,056	452,247	1,427,696
Proceeds from calls, maturities and paydowns of securities held to maturity	4,207	6,112	6,663
Proceeds from sales of securities available for sale	20,012
Net change in outstanding warehouse lines of credit	59,867	(198,710)	(67,298)
Purchase of non-business acquisition loans, including premiums paid	(6,160)	(51,868)	(117,516)
Net change in other loans	(268,839)	(125,756)	(100,660)
Proceeds from sale of mortgage loans transferred to held for sale		72,330
Proceeds from redemption of Federal Home Loan Bank stock		224
Purchase of Federal Home Loan Bank stock	(3,859)
Proceeds from sales of other real estate owned	2,793	4,595	9,412
Proceeds from sale of banking center			1,623
Net purchases of premises and equipment	(12,383)	(7,031)	(5,319)
Net cash used in investing activities	(287,113)	(296,134)	(358,208)
FINANCING ACTIVITIES:
Net change in deposits	272,466	468,544	429,295
Net change in securities sold under agreements to repurchase and other short-term borrowings	30,548	(221,960)	39,325
Payments of Federal Home Loan Bank advances	(490,000)	(292,000)	(218,000)
Proceeds from Federal Home Loan Bank advances	425,000	395,000	210,000
Payoff of subordinated note, net of common security interest		(4,000)
Repurchase of Class A Common Stock	(1,048)	(1,207)	(551)
Net proceeds from Class A Common Stock options exercised	68	80	1,136
Cash dividends paid	(17,656)	(16,768)	(15,839)
Net cash provided by financing activities	219,378	327,689	445,366
NET CHANGE IN CASH AND CASH EQUIVALENTS	10,042	79,227	137,204
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	289,309	210,082	72,878
CASH AND CASH EQUIVALENTS AT END OF PERIOD	299,351	289,309	210,082
Cash paid during the period for:
Interest	20,106	18,219	18,495
Income taxes	28,779	26,069	17,942
SUPPLEMENTAL NONCASH DISCLOSURES:
Transfers from loans to real estate acquired in settlement of loans	$ 841	4,778	2,938
Transfers from loans held for investment to held for sale		71,201
Loans provided for sales of other real estate owned		$ 256	$ 3,248