NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Nature of Operations [Abstract]
Trust Preferred securities payable	$ 70,680								$ 70,680								$ 70,680	$ 70,680
Number of retail banking offices	26																26
Cash and Cash Equivalents [Abstract]
Deposits with other financial institutions maturity, Maximum																	90 days
Loans [Abstract]
Principal or interest default period, Maximum																	90 days
Minimum performance period before a non-accrual loan is classified current																	6 months
Accounting for Goodwill and Other Intangible Assets [Abstract]
Goodwill	55,638								55,638								55,638	55,638
Income Taxes [Abstract]
Percentage of more likely than not tax position that would be sustained in a tax examination	50.00%																50.00%
Earnings Per Share Reconciliation [Abstract]
Net income	6,735		11,795		11,531		10,247		12,727		11,164		12,338		11,080		40,308	47,309	41,389
Less: Dividends paid on earnings allocated to participating securities																	(184)	(180)	(176)
Income attributable to common stock																	40,124	47,129	41,213
Weighted Average Number Of Shares Outstanding Including Participating Securities Basic																	34,296,288	33,723,102	33,260,652
Less: weighted average participating securities																	(327)	(318)	(304)
Weighted average shares outstanding utilized in the calculation of basic EPS																	34,295,961	33,722,784	33,260,348
Earnings Per Share, Basic	$ 0.19	[1]	$ 0.34	[1]	$ 0.34	[1]	$ 0.30	[1]	$ 0.38	[2]	$ 0.33	[2]	$ 0.37	[2]	$ 0.33	[2]	$ 1.18	$ 1.4	$ 1.24
Income attributable to common stock																	40,124	47,129	41,213
Weighted average common shares outstanding																	34,295,961	33,722,784	33,260,348
Common stock equivalents resulting from the dilutive effect of "in-the-money" stock options																	68,492	78,643	106,214
Weighted average shares outstanding utilized in the calculation of diluted EPS (in shares)																	34,364,453	33,801,427	33,366,562
Earnings Per Share, Diluted	$ 0.19	[1]	$ 0.34	[1]	$ 0.34	[1]	$ 0.30	[1]	$ 0.38	[2]	$ 0.33	[2]	$ 0.36	[2]	$ 0.33	[2]	$ 1.17	$ 1.40	$ 1.24
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average shares excluded from earnings per share calculation (in shares)																	1,279,708	2,116,374	2,600,100
Accumulated Other Comprehensive Income (Loss) [Abstract]
Non-credit component OTTI							510										510
Net Change in Non-Credit OTTI During the Period																	(162)
Non-credit component OTTI	348								510								348	510
Unamortized loss on investment securities transferred from available for sale to held-to-maturity							806										806
Unamortized loss on investment securities transferred from available for sale to held-to-maturity, current period change																	(111)
Unamortized loss on investment securities transferred from available for sale to held-to-maturity	695								806								695	806
Unrealized gains on securities available for sale							(3,078)										(3,078)
Unrealized gains on securities available for sale, current period change																	1,900
Unrealized gains on securities available for sale	(1,178)								(3,078)								(1,178)	(3,078)
Unrealized loss on defined benefit plans							11,471										11,471
Unrealized loss on defined benefit plans, current period change																	(1,696)
Unrealized loss on defined benefit plans	9,775								11,471								9,775	11,471
Total accumulated other comprehensive loss	$ 9,640								$ 9,709								$ 9,640	$ 9,709
Building [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Depreciation (in hundredths)																	2.22%
Building [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Depreciation (in hundredths)																	2.50%
Furniture, Fixtures, Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Depreciation (in hundredths)																	10.00%
Furniture, Fixtures, Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Depreciation (in hundredths)																	10.00%

[1] (2) The quarterly EPS amounts, when added, may not coincide with the full fiscal year EPS reported on the Consolidated Statements of Operations due to differences in the computed weighted average shares outstanding as well as rounding differences.

[2] (1) The quarterly EPS amounts, when added, may not coincide with the full fiscal year EPS reported on the Consolidated Statements of Operations due to differences in the computed weighted average shares outstanding as well as rounding differences.