Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 161,625	$ 149,502	$ 157,894
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	13,182	2,250	12,500
Depreciation and amortization of premises and equipment	27,403	27,605	24,555
Net amortization of investment security premiums	10,430	7,330	5,120
Deferred income tax expense	11,054	13,424	18,523
Investment securities gains, net	(2,550)	(9,066)	(2,041)
Gains on sales of mortgage loans	(15,685)	(13,264)	(10,063)
Proceeds from sales of mortgage loans held for sale	709,316	757,850	654,654
Originations of mortgage loans held for sale	(705,442)	(743,950)	(640,762)
Intangible amortization	0	247	1,259
Amortization of issuance costs and discount of long-term debt	617	582	337
Stock-based compensation	6,556	5,938	5,865
Excess tax benefits from stock-based compensation	(964)	(201)	(81)
(Increase) decrease in accrued interest receivable	(3,527)	(949)	2,219
Loss on redemption of trust preferred securities	0	5,626	0
Increase in other assets	(29,940)	(22,987)	(23,619)
(Decrease) increase in accrued interest payable	(1,092)	(7,321)	2,827
Increase in other liabilities	4,427	4,928	1,522
Total adjustments	23,785	28,042	52,815
Net cash provided by operating activities	185,410	177,544	210,709
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales of securities available for sale	115,844	66,480	32,227
Proceeds from maturities and paydowns of securities available for sale	558,854	439,533	417,559
Purchase of securities available for sale	(782,765)	(683,839)	(164,769)
Decrease (increase) in short-term investments	1,264	130,567	(174,922)
Net increase in loans	(873,939)	(743,655)	(360,982)
Net purchases of premises and equipment	(19,674)	(27,113)	(24,561)
Net cash used in investing activities	(1,000,416)	(818,027)	(275,448)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in demand and savings deposits	992,253	971,312	722,791
Net (decrease) increase in time deposits	(111,706)	(206,501)	153,529
Increase (decrease) in short-term borrowings	43,654	167,944	(928,910)
Additions to long-term debt	215,884	347,778	262,113
Repayments of long-term debt	(236,640)	(540,079)	(6,621)
Net proceeds from issuance of common stock	16,167	10,607	8,201
Excess tax benefits from stock-based compensation	964	201	81
Dividends paid	(69,382)	(65,361)	(64,028)
Acquisition of treasury stock	(18,545)	(50,000)	(175,255)
Deferred accelerated stock repurchase payment	0	0	(20,000)
Net cash provided by (used in) financing activities	832,649	635,901	(48,099)
Net Increase (decrease) in Cash and Due From Banks	17,643	(4,582)	(112,838)
Cash and Due From Banks at Beginning of Year	101,120	105,702	218,540
Cash and Due From Banks at End of Year	118,763	101,120	105,702
Cash paid during period for:
Interest	83,420	91,116	78,384
Income taxes	$ 16,193	$ 13,378	$ 16,778