CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
OPERATING ACTIVITIES:
Net income	$ 35,166	$ 28,787	$ 25,423
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization on investment securities, net	729	424	394
Accretion on loans, net	(2,835)	(6,263)	(9,479)
Depreciation of premises and equipment	6,742	6,363	5,311
Amortization of mortgaging servicing rights	1,400	1,330	2,173
Amortization of core deposit intangible asset			510
Provision for loan and lease losses	5,396	2,859	2,983
Net gain on sale of mortgage loans held for sale	(3,915)	(2,440)	(6,979)
Origination of mortgage loans held for sale	(160,989)	(82,457)	(291,155)
Proceeds from sale of mortgage loans held for sale	167,209	82,015	305,242
Origination of other loans held for sale	(137,551)
Proceeds from sale of other loans held for sale	137,037
Net realized recovery of value in mortgage servicing rights			(345)
Net realized gain on sales, calls and impairment of securities	(88)
Net gain realized on sale of other real estate owned	(956)	(883)	(2,170)
Writedowns of other real estate owned	1,257	3,101	1,824
Net gain on sale of banking center	(28)
Deferred director compensation expense - Company Stock	223	187	193
Stock based compensation expense	422	458	503
Bargain purchase gains on acquisition			(1,324)
Increase in cash surrender value of bank owned life insurance	(1,402)	(1,329)	(86)
Net change in other assets and liabilities:
Accrued interest receivable	(426)	(535)	973
Accrued interest payable	(33)	(197)	56
Other assets	(2,785)	(2,145)	488
Other liabilities	5,473	(2,570)	(12,278)
Net cash provided by operating activities	50,046	26,705	22,257
INVESTING ACTIVITIES:
Purchases of securities available for sale	(1,512,809)	(876,854)	(194,527)
Purchases of securities to be held to maturity			(15,000)
Proceeds from calls, maturities and paydowns of securities available for sale	1,427,696	875,978	195,553
Proceeds from calls, maturities and paydowns of securities to be held to maturity	6,663	5,137	10,294
Net change in outstanding warehouse lines of credit	(67,298)	(169,855)	67,000
Purchase of loans, including premiums paid	(117,516)	(235,824)
Net change in other loans	(100,660)	(46,383)	(11,048)
Proceeds from redemption of Federal Home Loan Bank stock		134	35
Proceeds from sales of other real estate owned	9,412	9,532	21,267
Proceeds from sale of banking center	1,623
Net purchases of premises and equipment	(5,319)	(7,759)	(5,022)
Purchase of bank owned life insurance		(25,000)	(25,000)
Net cash (used in) provided by investing activities	(358,208)	(470,894)	43,552
FINANCING ACTIVITIES:
Net change in deposits	429,295	67,325	7,929
Net change in securities sold under agreements to repurchase and other short-term borrowings	39,325	190,553	(85,329)
Payments of Federal Home Loan Bank advances	(218,000)	(188,000)	(37,600)
Proceeds from Federal Home Loan Bank advances	210,000	290,500	100,000
Repurchase of Common Stock	(551)	(347)	(4,095)
Net proceeds from Common Stock options exercised	1,136	1,103	467
Cash dividends paid	(15,839)	(14,930)	(14,009)
Net cash provided by (used in) financing activities	445,366	346,204	(32,637)
NET CHANGE IN CASH AND CASH EQUIVALENTS	137,204	(97,985)	33,172
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	72,878	170,863	137,691
CASH AND CASH EQUIVALENTS AT END OF YEAR	210,082	72,878	170,863
Cash paid during the period for:
Interest	18,495	19,801	21,337
Income taxes	17,942	18,828	31,875
SUPPLEMENTAL NONCASH DISCLOSURES:
Transfers from loans to real estate acquired in settlement of loans	2,938	7,333	15,271
Loans provided for sales of other real estate owned	$ 3,248	$ 1,442	$ 2,377