CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net income	$ 45,355	$ 38,200	$ 44,422
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,305	7,157	8,021
Provision (credit) for loan and lease losses	5,371	(163)	(1,084)
Share based compensation expense	1,979	1,452	1,688
Deferred income tax expense	(3)	808	3,348
Origination of loans held for sale	(193,316)	(137,339)	(251,878)
Proceeds from sales of loans held for sale	191,232	137,131	284,291
Gains on sales of loans held for sale	(2,861)	(1,939)	(4,629)
Loss on sales of other real estate owned	267	161	1,064
Investment securities gains	(36)	(5)	(115)
Gains (loss) on sales of premises and equipment	0	0	20
Increase (Decrease) in Operating Capital [Abstract]
Net (increase) decrease in accrued interest receivable	(809)	(102)	(140)
Net (increase) decrease in other assets	(2,015)	(6,866)	4,053
Net increase (decrease) in accrued expenses and other liabilities	(6,267)	20,166	(5,965)
Other - net	4,628	(4,997)	13,046
Net cash provided by operating activities	50,830	53,664	96,142
Investing activities:
Purchases of other equity securities		(750)	(7,051)
Proceeds of other equity securities	101
Purchases of investments held-to-maturity	(2,100)	0	(20,666)
Purchases of investments available-for-sale	(46,190)	0	(161,379)
Proceeds from maturities, calls and principal payments of investments held-to-maturity	12,943	3,786	11,090
Proceeds from maturities, calls and principal payments of investments available-for-sale	121,994	89,076	198,410
Net increase in loans and leases	(372,203)	(346,373)	(259,008)
Proceeds from the sales of other real estate owned	2,112	488	7,780
Expenditures for premises and equipment	(8,572)	(8,564)	(2,366)
Net cash used in investing activities	(291,915)	(262,337)	(233,190)
Financing activities:
Net increase (decrease) in deposits	197,221	189,284	(35,809)
Net increase (decrease) in retail repurchase agreements and federal funds purchased	34,713	20,590	(33,087)
Proceeds from advances from FHLB	2,274,000	1,805,000	1,075,000
Repayment of advances from FHLB	(2,244,000)	(1,765,000)	(865,058)
Proceeds from issuance of common stock	487	394	153
Tax benefits associated with shared based compensation	350	321	0
Repurchase of common stock	(22,624)	(910)	0
Dividends paid	(22,397)	(19,216)	(16,130)
Net cash provided by financing activities	217,750	230,463	125,069
Net increase (decrease) in cash and cash equivalents	(23,335)	21,790	(11,979)
Cash and cash equivalents at beginning of period	96,217	74,427	86,406
Cash and cash equivalents at end of period	72,882	96,217	74,427
Supplemental Disclosures:
Interest payments	20,040	18,833	19,610
Income tax payments	21,060	15,154	20,010
Transfers from loans to other real estate owned	$ 1,947	$ 2,446	$ 2,764