Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Operating Activities:
Net income	$ 39,528	$ 37,817	$ 115,510	$ 95,058
Adjustment to reconcile net income to net cash provided by operating activities:
Provision for credit losses	500		2,500	3,000
Depreciation and amortization			19,581	19,023
Amortization of intangibles	994	923	3,034	2,672
Amortization of debt securities premium and discount, net			5,345	7,751
Share-based compensation expense			6,987	6,856
Security gains, net	(5)	(1)	(1,099)	(89)
Net deferred loan origination expense			(5,141)	(5,059)
Increase in interest receivable			(2,449)	(682)
Increase (decrease) in interest payable			851	1,036
Realized gain on mortgages sold			(37,017)	(40,209)
Proceeds from mortgages sold			1,080,551	1,249,605
Origination of mortgages held for sale			(1,016,090)	(1,256,131)
Loss on other real estate owned, net	(164)	(525)	1,125	2,254
Increase in bank-owned life insurance			(6,079)	(5,481)
Other, net			7,338	15,465
Net cash provided by (used in) operating activities			174,947	95,069
Investing activities:
Proceeds from calls and maturities of available-for-sale securities			425,719	315,221
Proceeds from sales of available-for-sale securities			1,071	15
Purchases of available-for-sale securities			(266,808)	(690,820)
Net increase in loans and leases			(250,290)	(293,761)
Purchases of premises and equipment			(27,050)	(17,637)
Proceeds from sale of premises and equipment			288	1,362
Proceeds from death benefits from COLI			5,366
Acquisition of Insurance Agency				(3,716)
Proceeds from sale of other real estate owned			5,899	10,352
Other, net			(356)	(87)
Net cash provided by (used in) investing activities			(106,161)	(679,071)
Financing activities:
Net increase in deposits			87,847	258,898
Net decrease in short-term debt and other liabilities			42	1,023
Advances of long-term debt				500,000
Repayment of long-term debt				(6,280)
Redemption of Junior Subordinated Debt			(12,888)
Issuance of common stock			880	1,879
Repurchase of common stock			(111,739)	(14,162)
Payment of cash dividends			(35,706)	(30,599)
Net cash provided by financing activities			(71,564)	710,759
Increase in cash and cash equivalents			(2,778)	126,757
Cash and cash equivalents at beginning of period			222,965	197,969	$ 197,969
Cash and cash equivalents at end of period	$ 220,187	$ 324,726	220,187	324,726	$ 222,965
Supplemental Cash Flow Information
Income tax (refunds) payments, net			61,368	36,897
Interest paid			27,408	20,634
Transfers of loans to other real estate owned			5,173	9,266
MSR fair value adjustment			(671)	(10,233)
Financed sales of other real estate owned			1,442	$ 673
Transfers of loans held for sale to loan portfolio			$ 642