OTHER COMPREHENSIVE INCOME : OTHER COMPREHENSIVE INCOME (LOSS)-Reclassifications (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net securities gains (losses)									$ (3)		$ 423		$ 886
Income tax expense									(14,189)		(13,767)		(13,818)
NET INCOME	9,181	8,272	8,488	7,831	8,923	8,472	6,446	7,693	33,772		31,534		32,812
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
NET INCOME									(463)		(10,315)		(1,799)
Unrealized Gains and Losses on Available-for-Sale Securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net securities gains (losses)									(3)		423		886
Income tax expense									1		(169)		(354)
NET INCOME									(2)		254		532
Retirement Plans | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Change in funded status of post retirement benefits									(756)	[1]	(17,615)	[1]	(3,885)	[1]
Income tax expense									295		7,046		1,554
NET INCOME									$ (461)		$ (10,569)		$ (2,331)

[1] Included in the computation of net periodic benefit cost which is included in salaries and benefits. (see Footnote 15 for additional details).