GOODWILL AND OTHER INTANGIBLE ASSETS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011		Sep. 30, 2010	Dec. 31, 2010
Carrying amounts of goodwill [Roll Forward]
Balance, beginning of period			$ 270,097	[1]
Goodwill recorded during the period			1,200
Balance, end of period	271,297	270,097	271,297		270,097
Amortized intangible assets [Abstract]
Gross Carrying Amount	60,625		60,625			60,312
Accumulated Amortization	43,887		43,887			41,377
Aggregate amortization expense [Abstract]
Total	822	961	2,510		2,960
Estimated Amortization Expense: [Abstract]
For year ending December 31, 2011			3,328
For year ending December 31, 2012			2,957
For year ending December 31, 2013			2,268
For year ending December 31, 2014			1,961
For year ending December 31, 2015			1,315
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		217,618
Minimum percentage of fair value over carrying value for goodwill impairment analysis (in hundredths)	2.00%		2.00%
Insurance Agencies [Member]
Carrying amounts of goodwill [Roll Forward]
Balance, beginning of period			52,479
Goodwill recorded during the period			1,200
Balance, end of period	53,679		53,679
Minimum percentage of fair value over carrying value for goodwill impairment analysis (in hundredths)	30.00%		30.00%
Core deposit intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	27,801		27,801			27,801
Accumulated Amortization	20,480		20,480			19,716
Aggregate amortization expense [Abstract]
Total	248	324	764		986
Estimated Amortization Expense: [Abstract]
For year ending December 31, 2011			1,016
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			157
Customer relationship intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	32,749		32,749			32,511
Accumulated Amortization	23,379		23,379			21,661
Aggregate amortization expense [Abstract]
Total	565	637	1,718		1,974
Estimated Amortization Expense: [Abstract]
For year ending December 31, 2011			2,274
For year ending December 31, 2012			1,974
For year ending December 31, 2013			1,686
For year ending December 31, 2014			1,435
For year ending December 31, 2015			1,158
Non-solicitation intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	75		75			0
Accumulated Amortization	28		28			0
Aggregate amortization expense [Abstract]
Total	9	0	28		0
Estimated Amortization Expense: [Abstract]
For year ending December 31, 2011			38
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
Trade names [Member]
Unamortized intangible assets [Abstract]
Gross Carrying Amount	$ 688		$ 688			$ 688

[1] Derived from audited financial statements.