GOODWILL AND OTHER INTANGIBLE ASSETS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012	Dec. 31, 2012
Carrying amounts of goodwill [Roll Forward]
Balance, beginning of period	$ 275,173	[1]
Goodwill recorded during the year	0
Balance, end of period	275,173		271,297
Amortized intangible assets [Abstract]
Gross Carrying Amount	64,565			64,565
Accumulated Amortization	48,666			47,923
Aggregate amortization expense [Abstract]
Total	743		763
Estimated Amortization Expense [Abstract]
For year ending December 31, 2013	2,833
For year ending December 31, 2014	2,496
For year ending December 31, 2015	2,059
For year ending December 31, 2016	1,612
For year ending December 31, 2017	1,411
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	21,831			21,674
Aggregate amortization expense [Abstract]
Total	157		243
Estimated Amortization Expense [Abstract]
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
For year ending December 31, 2017	419
Customer relationship intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	36,239			36,239
Accumulated Amortization	26,646			26,098
Aggregate amortization expense [Abstract]
Total	548		511
Estimated Amortization Expense [Abstract]
For year ending December 31, 2013	2,101
For year ending December 31, 2014	1,820
For year ending December 31, 2015	1,497
For year ending December 31, 2016	1,161
For year ending December 31, 2017	992
Non-solicitation intangibles [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	525			525
Accumulated Amortization	189			151
Aggregate amortization expense [Abstract]
Total	38		9
Estimated Amortization Expense [Abstract]
For year ending December 31, 2013	150
For year ending December 31, 2014	150
For year ending December 31, 2015	75
For year ending December 31, 2016	0
For year ending December 31, 2017	0
Community Banking [Member]
Carrying amounts of goodwill [Roll Forward]
Balance, beginning of period	217,618
Goodwill recorded during the year	0
Balance, end of period	217,618
Insurance Agencies [Member]
Carrying amounts of goodwill [Roll Forward]
Balance, beginning of period	57,555
Goodwill recorded during the year	0
Balance, end of period	$ 57,555

[1] Derived from audited financial statements.