FAIR VALUE DISCLOSURES (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Mortgage Servicing Rights [Member]	Mar. 31, 2011 Mortgage Servicing Rights [Member]	Mar. 31, 2012 Derivative Instruments, Net [Member]	Mar. 31, 2011 Derivative Instruments, Net [Member]	Mar. 31, 2012 Available-for-sale Securities [Member]	Mar. 31, 2011 Available-for-sale Securities [Member]	Mar. 31, 2012 Carrying Value [Member]	Dec. 31, 2011 Carrying Value [Member]	Mar. 31, 2012 Fair Value [Member]	Dec. 31, 2011 Fair Value [Member]	Mar. 31, 2012 Fair Value, Measurements, Recurring [Member]	Mar. 31, 2011 Fair Value, Measurements, Recurring [Member]	Mar. 31, 2012 Fair Value, Measurements, Recurring [Member] Level 1 [Member]	Mar. 31, 2011 Fair Value, Measurements, Recurring [Member] Level 1 [Member]	Mar. 31, 2012 Fair Value, Measurements, Recurring [Member] Level 2 [Member]	Mar. 31, 2011 Fair Value, Measurements, Recurring [Member] Level 2 [Member]	Mar. 31, 2012 Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Mar. 31, 2011 Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Mar. 31, 2012 Fair Value, Measurements, Nonrecurring [Member]	Mar. 31, 2011 Fair Value, Measurements, Nonrecurring [Member]	Mar. 31, 2012 Fair Value, Measurements, Nonrecurring [Member] Total Losses [Member]	Mar. 31, 2011 Fair Value, Measurements, Nonrecurring [Member] Total Losses [Member]	Mar. 31, 2012 Fair Value, Measurements, Nonrecurring [Member] Level 1 [Member]	Mar. 31, 2011 Fair Value, Measurements, Nonrecurring [Member] Level 1 [Member]	Mar. 31, 2012 Fair Value, Measurements, Nonrecurring [Member] Level 2 [Member]	Mar. 31, 2011 Fair Value, Measurements, Nonrecurring [Member] Level 2 [Member]	Mar. 31, 2012 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member]	Mar. 31, 2011 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member]
Available-for-sale securities:
U.S. Government agencies											$ 1,578,441	$ 459,763	$ 0	$ 0	$ 1,578,441	$ 459,763	$ 0	$ 0
Government agency issued residential mortgage-backed securities											385,146	529,302	0	0	385,146	529,302	0	0
Government agency issued commercial mortgage-backed securities											31,647	30,938	0	0	31,647	30,938	0	0
Obligations of states and political subdivisions											568,642	111,380	0	0	568,642	111,380	0	0
Other											9,659	14,080	665	638	8,994	13,442	0	0
Mortgage servicing rights											35,668	42,306	0	0	0	0	35,668	42,306
Derivative instruments											53,057	33,120	0	0	0	0	53,057	33,120
Liabilities:
Derivative instruments											51,208	32,766	0	0	0	0	51,208	32,766
Assets:
Loans held for sale							110,294	83,458	110,323	83,503									110,294	56,876	0	0	0	0	110,294	56,876	0	0
Impaired loans																			211,112	338,821	(25,546)	(49,419)	0	0	0	0	211,112	338,821
Other real estate owned																			167,808	136,412	(26,520)	(14,738)	0	0	0	0	167,808	136,412
Total																			2,662,260	1,220,889			665	638	2,572,870	1,144,825	88,725	75,426
Changes in fair value of net assets (liabilities) classified as Level 3 [Roll Forward]
Beginning Balance	30,174	38,642	342	2,685	0	0
Year to date net gains (losses) included in:
Net (loss) income	5,494	3,664	1,507	(2,331)	0	0
Other comprehensive income	0	0	0	0	0	0
Purchases, sales, issuances and settlements, net	0	0	0	0	0	0
Transfers in and/or out of Level 3	0	0	0	0	0	0
Ending Balance	35,668	42,306	1,849	354	0	0
Net unrealized (losses) gains included in net income for the quarter relating to assets and liabilities held	3,697	2,540	1,507	(2,331)	0	0
Assets:
Cash and due from banks							184,441	195,681	184,441	195,681
Interest bearing deposits with other banks							665,675	303,663	665,675	303,663
Available-for-sale securities							2,573,535	2,513,518	2,573,535	2,513,518
Net loans and leases							8,556,146	8,675,193	8,605,943	8,730,819
Loans held for sale							110,294	83,458	110,323	83,503									110,294	56,876	0	0	0	0	110,294	56,876	0	0
Liabilities:
Noninterest bearing deposits							2,260,012	2,269,799	2,260,012	2,269,799
Savings and interest bearing deposits							5,964,841	5,698,527	5,964,841	5,698,527
Other time deposits							2,857,469	2,986,863	2,901,829	3,029,147
Federal funds purchased and securities sold under agreement to repurchase and other short-term borrowings							402,589	375,433	402,121	375,285
Long-term debt and other borrowings							193,877	193,880	205,974	200,166
Derivative instruments:
Forward commitments to sell fixed rate mortgage loans							(98)	(1,057)	(98)	(1,057)
Commitments to fund fixed rate mortgage loans							2,710	2,140	2,710	2,140
Interest rate swap position to receive							50,094	53,608	50,094	53,608
Interest rate swap position to pay							$ (50,857)	$ (54,349)	$ (50,857)	$ (54,349)