PARENT COMPANY FINANCIAL STATEMENTS (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets
Other assets	$ 367,610	$ 324,369
Total assets	21,283,652	20,997,298
Liabilities and Shareholders' Equity
Short-term borrowings	568,505	615,222
Long-term obligations	444,921	687,599
Other liabilities	218,553	178,209
Stockholders' equity	1,864,007	1,861,128	1,732,962	1,559,115
Total liabilities and shareholders' equity	21,283,652	20,997,298
Income Statement [Abstract]
Interest expense	90,148	144,192	195,125
Net interest income (loss)	914,688	870,967	774,243
Income tax benefit	59,822	115,103	110,518
Net income	134,348	195,028	193,044
OPERATING ACTIVITIES
Net income	134,348	195,028	193,044
Net amortization of premiums and accretion of discounts	(158,227)	(194,434)	(119,085)
Gain on retirement of long-term obligations	0	(9,685)	0
Securities (gains) losses	(2,277)	288	(1,952)
Other than temporary impairment on securities	0	0
Change in other assets	(17,617)	89,979	(6,810)
Change in other liabilities	23,967	(1,541)	21,455
INVESTING ACTIVITIES
Net change in short-term borrowings	(101,717)	(283,440)	(500,217)
Retirement of long-term obligations	(196,338)	(320,730)	(114,425)
Repurchase of common stock	(103,624)	(24,387)	0
Cash dividends paid	(15,398)	(12,499)	(12,521)
Net change in cash	48,929	130,623	(20,064)
Cash and due from banks at beginning of period	590,801	460,178	480,242
Cash and due from banks at end of period	639,730	590,801	460,178
Cash payments for
Interest	104,514	157,477	196,002
Income taxes	66,453	91,465	187,183
Parent [Member]
Assets
Cash	2,131	10,765
Investment securities	237,765	235,617
Investment in subsidiaries	1,969,600	2,031,229
Due from subsidiaries	78,512	120,836
Other assets	83,283	114,852
Total assets	2,371,291	2,513,299
Liabilities and Shareholders' Equity
Short-term borrowings	399,047	375,396
Long-term obligations	96,392	251,697
Other liabilities	11,845	25,078
Stockholders' equity	1,864,007	1,861,128
Total liabilities and shareholders' equity	2,371,291	2,513,299
Income Statement [Abstract]
Interest income	1,353	1,345	1,524
Interest expense	15,435	21,512	22,633
Net interest income (loss)	(14,082)	(20,167)	(21,109)
Dividends from subsidiaries	179,588	82,812	50,424
Other income (loss)	2,843	9,699	(314)
Other operating expense	6,384	5,298	2,343
Income before income tax benefit and equity in undistributed net income of subsidiaries	161,965	67,046	26,658
Income tax benefit	(8,417)	(5,531)	(8,343)
Income before equity in undistributed net income of subsidiaries	170,382	72,577	35,001
(Excess distributions) equity in undistributed net income of subsidiaries	(36,034)	122,451	158,043
Net income	134,348	195,028	193,044
OPERATING ACTIVITIES
Net income	134,348	195,028	193,044
Undistributed net income of subsidiaries	36,034	(122,451)	(158,043)
Net amortization of premiums and accretion of discounts	439	203	(113)
Gain on retirement of long-term obligations	0	(9,685)	0
Securities (gains) losses	(2,274)	(62)	(44)
Other than temporary impairment on securities	45	26	421
Change in other assets	30,761	(20,951)	(30,443)
Change in other liabilities	(10,148)	(1,925)	1,409
Net cash provided by (Used in) Operating Activities	189,205	40,183	6,231
INVESTING ACTIVITIES
Net change in due from subsidiaries	42,323	146,463	59,249
Purchases of investment securities	(111,409)	(220,387)	(75,180)
Maturities and sales of investment securities	112,625	75,151	65,991
Investment in subsidiaries	9,298	0	(14,000)
Net Cash Provided by (Used in) Investing Activities	52,837	1,227	36,060
Net change in short-term borrowings	23,651	4,046	(24,227)
Retirement of long-term obligations	(155,305)	(11,815)	0
Repurchase of common stock	(103,624)	(24,387)	0
Cash dividends paid	(15,398)	(12,499)	(12,521)
Net cash used by financing activities	(250,676)	(44,655)	(36,748)
Net change in cash	(8,634)	(3,245)	5,543
Cash and due from banks at beginning of period	10,765	14,010	8,467
Cash and due from banks at end of period	2,131	10,765	14,010
Cash payments for
Interest	25,574	20,677	22,003
Income taxes	$ 66,453	$ 91,465	$ 187,183