Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 149,502	$ 157,894	$ 161,840
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	2,250	12,500	40,500
Depreciation and amortization of premises and equipment	27,605	24,555	25,911
Net amortization of investment security premiums	7,330	5,120	10,002
Deferred income tax expense	13,424	18,523	11,825
Investment securities gains, net	(9,066)	(2,041)	(8,004)
Gains on sales of mortgage loans	(13,264)	(10,063)	(24,609)
Proceeds from sales of mortgage loans held for sale	757,850	654,654	1,424,896
Originations of mortgage loans held for sale	(743,950)	(640,762)	(1,353,739)
Intangible amortization	247	1,259	2,438
Stock-based compensation	5,938	5,865	5,330
Excess tax benefits from stock-based compensation	(201)	(81)	(302)
(Increase) decrease in accrued interest receivable	(949)	2,219	1,749
Loss on redemption of trust preferred securities	5,626	0	0
Increase (decrease) in other assets	(9,931)	(8,803)	37,236
(Decrease) increase in accrued interest payable	(7,321)	2,827	(4,112)
Decrease in other liabilities	(8,128)	(13,294)	(29,344)
Total adjustments	27,460	52,478	139,777
Net cash provided by operating activities	176,962	210,372	301,617
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales of securities available for sale	66,480	32,227	267,126
Proceeds from maturities and paydowns of securities available for sale	439,533	417,559	637,851
Purchase of securities available for sale	(683,839)	(164,769)	(776,352)
Decrease (increase) in short-term investments	130,567	(174,922)	(3,202)
Net increase in loans	(743,655)	(360,982)	(699,961)
Net purchases of premises and equipment	(27,113)	(24,561)	(24,209)
Net cash used in investing activities	(818,027)	(275,448)	(598,747)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in demand and savings deposits	971,312	722,791	472,439
Net (decrease) increase in time deposits	(206,501)	153,529	(465,416)
Increase (decrease) in short-term borrowings	167,944	(928,910)	390,230
Additions to long-term debt	347,778	262,113	0
Repayments of long-term debt	(539,497)	(6,284)	(10,669)
Net proceeds from issuance of common stock	10,607	8,201	9,936
Excess tax benefits from stock-based compensation	201	81	302
Dividends paid	(65,361)	(64,028)	(46,525)
Acquisition of treasury stock	(50,000)	(175,255)	(90,927)
Deferred accelerated stock repurchase payment	0	(20,000)	0
Net cash provided by (used in) financing activities	636,483	(47,762)	259,370
Net Decrease in Cash and Due From Banks	(4,582)	(112,838)	(37,760)
Cash and Due From Banks at Beginning of Year	105,702	218,540	256,300
Cash and Due From Banks at End of Year	101,120	105,702	218,540
Cash paid during period for:
Interest	91,116	78,384	86,607
Income taxes	$ 13,378	$ 16,778	$ 32,605