CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net income	$ 48,250	$ 45,355	$ 38,200
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,958	7,305	7,157
Provision (credit) for loan losses	5,546	5,371	(163)
Share based compensation expense	2,139	1,979	1,452
Deferred income tax expense	349	(3)	808
Origination of loans held for sale	(196,726)	(193,316)	(137,339)
Proceeds from sales of loans held for sale	239,705	191,232	137,131
Gains on sales of loans held for sale	(3,877)	(2,861)	(1,939)
Loss on sales of other real estate owned	48	267	161
Investment securities gains	(1,932)	(36)	(5)
Increase (Decrease) in Operating Capital [Abstract]
Net (increase) decrease in accrued interest receivable	(1,146)	(809)	(102)
Net (increase) decrease in other assets	(5,134)	(2,015)	(6,866)
Net increase (decrease) in accrued expenses and other liabilities	(2,932)	(6,267)	20,166
Other - net	(1,873)	4,628	(4,997)
Net cash provided by operating activities	90,375	50,830	53,664
Investing activities:
Purchases of other equity securities	(4,758)		(750)
Proceeds of other equity securities		101
Purchases of investments held-to-maturity	0	(2,100)	0
Purchases of investments available-for-sale	(287,211)	(46,190)	0
Proceeds from sales of investment available-for-sale	40,863	0	0
Proceeds from maturities, calls and principal payments of investments held-to-maturity	5,004	12,943	3,786
Proceeds from maturities, calls and principal payments of investments available-for-sale	298,803	121,994	89,076
Net increase in loans and leases	(469,942)	(372,203)	(346,373)
Proceeds from the sales of other real estate owned	1,393	2,112	488
Acquisition of business activity, net of cash acquired	(1,347)	0	0
Expenditures for premises and equipment	(5,798)	(8,572)	(8,564)
Net cash used in investing activities	(422,993)	(291,915)	(262,337)
Financing activities:
Net increase (decrease) in deposits	313,814	197,221	189,284
Net increase (decrease) in retail repurchase agreements and federal funds purchased	15,974	34,713	20,590
Proceeds from advances from FHLB	2,665,000	2,274,000	1,805,000
Repayment of advances from FHLB	(2,560,000)	(2,244,000)	(1,765,000)
Retirement of subordinated debt	(5,000)	0	0
Proceeds from issuance of common stock	897	487	394
Tax benefits associated with shared based compensation	125	350	321
Repurchase of common stock	(13,273)	(22,624)	(910)
Dividends paid	(23,676)	(22,397)	(19,216)
Net cash provided by financing activities	393,861	217,750	230,463
Net increase (decrease) in cash and cash equivalents	61,243	(23,335)	21,790
Cash and cash equivalents at beginning of period	72,882	96,217	74,427
Cash and cash equivalents at end of period	134,125	72,882	96,217
Supplemental Disclosures:
Interest payments	21,377	20,040	18,833
Income tax payments	22,331	21,060	15,154
Transfer of Investments Held-to-maturity to Available For Sale Securities	203,118	0	0
Transfer from loans to residential mortgage loans held for sale	36,867	0	0
Transfers from loans to other real estate owned	$ 637	$ 1,947	$ 2,446