CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Operating activities:
Net income	$ 13,474	$ 10,995	$ 34,934	$ 32,553
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			5,940	5,422
Provision (credit) for loan and lease losses	781	1,706	4,974	3,521	$ 5,371
Share based compensation expense			1,341	1,450
Deferred income tax expense			646	1,412
Origination of loans held for sale			(130,409)	(150,686)
Proceeds from sales of loans held for sale			151,077	153,020
Gains on sales of loans held for sale			(2,461)	(2,240)
Loss on sales of other real estate owned			48	224
Investment securities gains	0	(1)	(1,919)	(20)
Increase (Decrease) in Operating Capital [Abstract]
Net (increase) decrease in accrued interest receivable			320	(468)
Net (increase) decrease in other assets			(1,731)	(2,772)
Net increase (decrease) in accrued expenses and other liabilities			(5,999)	(176)
Other - net			(731)	3,063
Net cash provided by operating activities			56,030	44,303
Investing activities:
Proceeds of other equity securities			5,507	3,289
Purchases of investments held-to-maturity			0	(2,100)
Purchases of investments available-for-sale			(120,273)	0
Proceeds from sales of investment available-for-sale			40,863	0
Proceeds from maturities, calls and principal payments of investments held-to-maturity			5,004	4,791
Proceeds from maturities, calls and principal payments of investments available-for-sale			227,419	66,727
Net increase in loans and leases			(303,709)	(288,233)
Proceeds from the sales of other real estate owned			1,393	1,855
Acquisition of business activity, net of cash acquired			(1,347)	0
Expenditures for premises and equipment			(4,250)	(6,739)
Net cash used in investing activities			(149,393)	(220,410)
Financing activities:
Net increase (decrease) in deposits			273,427	209,159
Net increase (decrease) in retail repurchase agreements and federal funds purchased			15,060	46,946
Proceeds from advances from FHLB			1,805,000	1,649,000
Repayment of advances from FHLB			(1,940,000)	(1,694,000)
Retirement of subordinated debt			(5,000)	0
Proceeds from issuance of common stock			585	581
Tax benefits associated with shared based compensation			287	0
Repurchase of common stock			(13,273)	(18,869)
Dividends paid			(17,408)	(16,496)
Net cash provided by financing activities			118,678	176,321
Net increase (decrease) in cash and cash equivalents			25,315	214
Cash and cash equivalents at beginning of period			72,882	96,217	96,217
Cash and cash equivalents at end of period	$ 98,197	$ 96,431	98,197	96,431	$ 72,882
Supplemental Disclosures:
Interest payments			16,193	14,779
Income tax payments			16,825	14,825
Transfer of Investments Held-to-maturity to Available For Sale Securities			203,118	0
Transfer from loans to residential mortgage loans held for sale			18,572	0
Transfers from loans to other real estate owned			$ 0	$ 1,524