Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities:
Net income	$ 132,728	$ 127,491	$ 116,750
Adjustment to reconcile net income to net cash provided by operating activities:
Provision for credit losses	4,000	(13,000)
Depreciation and amortization	25,629	26,288	27,272
Deferred taxes	10,521	(11,356)	(7,563)
Amortization of intangibles	3,636	3,963	4,443
Amortization of debt securities premium and discount, net	10,060	12,565	13,089
Share-based compensation expense	7,097	5,585	1,201
Security gains, net	(128)	(136)	(37)
Net deferred loan origination expense	(6,587)	(6,677)	(6,809)
Excess tax benefit from exercise of stock options	(1,484)	(1,079)	(1,856)
Decrease in interest receivable	(1,104)	1,084	165
Decrease in interest payable	904	(329)	(1,436)
Realized gain on mortgages sold	(56,047)	(46,058)	(31,941)
Proceeds from mortgages sold	1,698,588	1,468,729	914,084
Origination of mortgages held for sale	(1,651,981)	(1,440,411)	(920,689)
Loss on other real estate owned, net	2,954	5,703	14,545
Increase in bank-owned life insurance	(7,585)	(7,457)	(8,848)
(Increase) decrease in prepaid pension asset			26,263
Other, net	(27,705)	8,401	3,496
Net cash provided by operating activities	143,496	133,306	142,129
Investing Activities:
Proceeds from calls and maturities of available-for-sale securities	419,197	415,795	584,260
Proceeds from sales of available-for-sale securities	35	1,110
Purchases of available-for-sale securities	(891,155)	(374,181)	(252,467)
Net (increase) decrease in loans and leases	(449,100)	(663,573)	(803,858)
Purchases of premises and equipment	(25,091)	(30,401)	(17,211)
Proceeds from sale of premises and equipment	2,041	549	527
Acquisition of businesses, net of cash acquired	(11,197)		(7,060)
Proceeds from sale of other real estate owned	13,719	20,723	35,264
Proceeds of bank-owned life insurance, net of proceeds from death benefits	470	2,999	1,206
Other, net	(156)	(25)	(20)
Net cash (used in) provided by investing activities	(941,237)	(627,004)	(459,359)
Financing Activities:
Net (decrease) increase in deposits	356,980	358,822	198,503
Net increase (decrease) in short-term debt and other liabilities	78,056	76,254	(32,877)
Redemption of junior subordinated debt securities	(10,310)		(8,248)
Advances of long-term debt	500,000		8,000
Repayment of long-term debt	(39,775)	(8,373)	(8,066)
Issuance of common stock	2,773	10,441	11,583
Repurchase of common stock	(24,161)	(70,438)	(711)
Excess tax (benefit) expense from exercise of stock options	1,484	1,079	1,856
Payment of cash dividends	(42,310)	(33,368)	(23,983)
Net cash (used in) provided by financing activities	822,737	334,417	146,057
(Decrease) increase in Cash and Cash Equivalents	24,996	(159,281)	(171,173)
Cash and Cash Equivalents at Beginning of Year	197,969	357,250	528,423
Cash and Cash Equivalents at End of Year	$ 222,965	$ 197,969	$ 357,250