GOODWILL AND OTHER INTANGIBLE ASSETS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012		Sep. 30, 2011	Dec. 31, 2011
Carrying amounts of goodwill [Roll Forward]
Balance, beginning of period			$ 271,297	[1]
Goodwill recorded during the period			3,876
Balance, end of period	275,173	271,297	275,173		271,297
Amortized intangible assets [Abstract]
Gross Carrying Amount	64,311		64,311			60,625
Accumulated Amortization	47,067		47,067			44,701
Aggregate amortization expense [Abstract]
Total	861	822	2,366		2,510
Estimated Amortization Expense:
For year ending December 31, 2012		3,217			3,217
For year ending December 31, 2013		2,791			2,791
For year ending December 31, 2014		2,458			2,458
For year ending December 31, 2015		2,027			2,027
For year ending December 31, 2016		1,584			1,584
Trade names [Member]
Unamortized intangible assets [Abstract]
Gross Carrying Amount	688		688			688
Core deposit intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	27,801		27,801			27,801
Accumulated Amortization	21,440		21,440			20,728
Aggregate amortization expense [Abstract]
Total	235	248	712		764
Estimated Amortization Expense:
For year ending December 31, 2012		946			946
For year ending December 31, 2013		582			582
For year ending December 31, 2014		526			526
For year ending December 31, 2015		487			487
For year ending December 31, 2016		451			451
Customer relationship intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	35,985		35,985			32,749
Accumulated Amortization	25,523		25,523			23,935
Aggregate amortization expense [Abstract]
Total	579	565	1,588		1,718
Estimated Amortization Expense:
For year ending December 31, 2012		2,159			2,159
For year ending December 31, 2013		2,059			2,059
For year ending December 31, 2014		1,782			1,782
For year ending December 31, 2015		1,465			1,465
For year ending December 31, 2016		1,133			1,133
Non-solicitation intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	525		525			75
Accumulated Amortization	104		104			38
Aggregate amortization expense [Abstract]
Total	47	9	66		28
Estimated Amortization Expense:
For year ending December 31, 2012		112			112
For year ending December 31, 2013		150			150
For year ending December 31, 2014		150			150
For year ending December 31, 2015		75			75
For year ending December 31, 2016		0			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		217,618
Insurance Agencies [Member]
Carrying amounts of goodwill [Roll Forward]
Balance, beginning of period			53,679
Goodwill recorded during the period			3,876
Balance, end of period	$ 57,555		$ 57,555

[1] Derived from audited financial statements.