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GOODWILL AND OTHER INTANGIBLE ASSETS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Carrying amounts of goodwill [Roll Forward]
Balance, beginning of period	$ 271,297
Goodwill recorded during the period	0
Balance, end of period	271,297	271,297
Amortized intangible assets [Abstract]
Gross Carrying Amount	60,625		60,625
Accumulated Amortization	45,463		44,701
Aggregate amortization expense [Abstract]
Total	762	854
Estimated Amortization Expense:
For year ending December 31, 2012	2,940
For year ending December 31, 2013	2,250
For year ending December 31, 2014	1,944
For year ending December 31, 2015	1,615
For year ending December 31, 2016	1,274
Trade names [Member]
Unamortized intangible assets [Abstract]
Gross Carrying Amount	688		688
Core deposit intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	27,801		27,801
Accumulated Amortization	20,971		20,728
Aggregate amortization expense [Abstract]
Total	243	267
Estimated Amortization Expense:
For year ending December 31, 2012	946
For year ending December 31, 2013	582
For year ending December 31, 2014	526
For year ending December 31, 2015	487
For year ending December 31, 2016	451
Customer relationship intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	32,749		32,749
Accumulated Amortization	24,445		23,935
Aggregate amortization expense [Abstract]
Total	510	578
Estimated Amortization Expense:
For year ending December 31, 2012	1,957
For year ending December 31, 2013	1,668
For year ending December 31, 2014	1,418
For year ending December 31, 2015	1,128
For year ending December 31, 2016	823
Non-solicitation intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	75		75
Accumulated Amortization	47		38
Aggregate amortization expense [Abstract]
Total	9	9
Estimated Amortization Expense:
For year ending December 31, 2012	37
For year ending December 31, 2013	0
For year ending December 31, 2014	0
For year ending December 31, 2015	0
For year ending December 31, 2016	0
Community Banking [Member]
Carrying amounts of goodwill [Roll Forward]
Balance, beginning of period	217,618
Goodwill recorded during the period	0
Balance, end of period	217,618
Insurance Agencies [Member]
Carrying amounts of goodwill [Roll Forward]
Balance, beginning of period	53,679
Goodwill recorded during the period	0
Balance, end of period	$ 53,679