OTHER COMPREHENSIVE INCOME (LOSS) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Other Comprehensive Income (Loss) [Abstract]
Change in unrealized loss on securities transferred to held to maturity, after tax	$ 13	$ 12
Tax expense (benefit)	7,925	7,177
Net income	11,778	10,034
Change in net unrealized gain during the period, tax	19	(30)
Change in net unrealized gain during the period, after tax	24	(37)
Total defined benefit plans, tax	(268)	118
Change in pension and other postretirement obligations, net of deferred tax (expense) benefit of $(268) and $118 during the three months ended March 31, 2015 and 2014, respectively	(329)	143
Total other comprehensive income, before tax	(1,910)	222
Total other comprehensive income, tax	(860)	100
Net other comprehensive income during during the period	(1,050)	122
Securities Held-To-Maturity and Transferred Securities [Member]
Other Comprehensive Income (Loss) [Abstract]
Change in non-credit component of OTTI, pre-tax	8	8
Change in non-credit component of OTTI, tax	4	4
Change in non-credit component of OTTI, after tax	4	4
Change in unrealized loss on securities transferred to held to maturity, pre-tax	24	20
Change in unrealized loss on securities transferred to held to maturity, tax	11	8
Change in unrealized loss on securities transferred to held to maturity, after tax	13	12
Total Securities held to maturity and transferred securities before tax	32	28
Total securities held to maturity and transferred tax	15	12
Total securities held to maturity and transferred securities, after tax	17	16
Securities Available-For-Sale [Member]
Other Comprehensive Income (Loss) [Abstract]
Change in net unrealized gain during the period, pre-tax	43	(67)
Change in net unrealized gain during the period, tax	19	(30)
Change in net unrealized gain during the period, after tax	24	(37)
Total securities available-for-sale, pre-tax	(1,345)	(67)
Total securities available-for-sale, tax	(607)	(30)
Total securities available-for-sale, after tax	(738)	(37)
Securities Available-For-Sale [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Other Comprehensive Income (Loss) [Abstract]
Reclassification adjustment for net gains included in net gain on securities	(1,388)	0
Tax expense (benefit)	(626)	0
Net income	(762)	0
Defined Benefit Plans [Member]
Other Comprehensive Income (Loss) [Abstract]
Change in the net actuarial gain or loss, pre-tax	(1,064)
Change in the net actuarial gain or loss, tax	(478)
Change in the net actuarial gain or loss, after tax	(586)
Total defined benefit plans, pre-tax	(597)	261
Total defined benefit plans, tax	(268)	118
Change in pension and other postretirement obligations, net of deferred tax (expense) benefit of $(268) and $118 during the three months ended March 31, 2015 and 2014, respectively	(329)	143
Defined Benefit Plans [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Other Comprehensive Income (Loss) [Abstract]
Reclassification adjustment for expense included in salaries and employee benefits expense	467	261
Tax expense (benefit)	210	118
Net income	$ 257	$ 143