Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Operating Activities:
Net income	$ 34,343	$ 28,778	$ 106,322	$ 88,090
Adjustment to reconcile net income to net cash provided by operating activities:
Provision for credit losses	(3,000)		(13,000)
Depreciation and amortization			19,914	20,336
Deferred taxes				(1,939)
Amortization of intangibles	949	1,126	3,042	3,332
Amortization of debt securities premium and discount, net			9,461	9,921
Share-based compensation expense			5,749	1,480
Security gains, net	(33)	(18)	(88)	(19)
Net deferred loan origination expense			(5,073)	(5,199)
Excess tax benefit from exercise of stock options			867	1,248
(Increase) decrease in interest receivable			386	(161)
Increase (decrease) in interest payable			(47)	(942)
Realized gain on mortgages sold			(34,965)	(24,543)
Proceeds from mortgages sold			1,134,164	781,368
Origination of mortgages held for sale			(1,130,433)	(793,850)
Loss on other real estate owned, net			2,956	10,485
Increase in bank-owned life insurance			(5,491)	(5,599)
Decrease in prepaid pension asset				4,244
Other, net			14,532	21,692
Net cash provided by operating activities			108,296	109,944
Investing activities:
Proceeds from calls and maturities of available-for-sale securities			276,707	426,015
Proceeds from sales of available-for-sale securities			1,110
Purchases of available-for-sale securities			(294,853)	(160,387)
Net (increase) decrease in loans and leases			(503,869)	(599,310)
Purchases of premises and equipment			(20,125)	(12,685)
Proceeds from sale of premises and equipment			549	336
Purchase of bank-owned life insurance, net of proceeds from death benefits			2,742	1,206
Acquisition of Insurance Agency				(5,060)
Proceeds from sale of other real estate owned, net			13,033	28,366
Other, net			(12)	(12)
Net cash (used in) provided by investing activities			(524,718)	(321,531)
Financing activities:
Net increase (decrease) in deposits			169,607	(72,299)
Net increase (decrease) in short-term debt and other liabilities			258,024	10,388
Advances of long-term debt				8,000
Repayment of advances of long-term debt			(6,280)	(5,972)
Redemption of Junior Subordinated Debt				(8,248)
Issuance of common stock			6,071	9,621
Repurchase of common stock			(70,439)	(675)
Excess tax benefit from exercise of stock options			(867)	(1,248)
Payment of cash dividends			(23,953)	(16,769)
Net cash provided by (used in) financing activities			332,163	(77,202)
Increase (decrease) in cash and cash equivalents			(84,259)	(288,789)
Cash and cash equivalents at beginning of period			357,250	528,423	$ 528,423
Cash and cash equivalents at end of period	$ 272,991	$ 239,634	$ 272,991	$ 239,634	$ 357,250