OTHER COMPREHENSIVE INCOME (LOSS) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other Comprehensive Income (Loss) [Abstract]
Tax expense (benefit)	$ 6,891	$ 7,215	$ 8,059	$ 7,176	$ 3,534	$ 8,280	$ 8,004	$ 7,072	$ 29,341	$ 26,890	$ 31,588
Net income	10,308	10,631	12,039	10,570	6,735	11,795	11,531	10,247	43,548	40,308	47,309
Change in net unrealized gain during the period, tax									(162)	1,102	615
Change in net unrealized gain during the period, after tax									201	(1,339)	(720)
Total defined benefit plans, tax									(3,765)	(1,395)	2,933
Total other comprehensive income (loss), net of tax									4,881	69	(3,357)
Securities Held-To-Maturity and Transferred Securities [Member]
Other Comprehensive Income (Loss) [Abstract]
Change in non-credit component of OTTI, pre-tax									32	296	1,274
Change in non-credit component of OTTI, tax									16	134	574
Change in non-credit component of OTTI, after tax									16	162	700
Change in unrealized loss on securities transferred to held to maturity, pre-tax									271	202	446
Change in unrealized loss on securities transferred to held to maturity, tax									122	91	201
Change in unrealized loss on securities transferred to held to maturity, after tax									149	111	245
Total Securities held to maturity and transferred securities, before tax									303	498	1,720
Total securities held to maturity and transferred, tax									138	225	775
Total securities held to maturity and transferred securities, after tax									165	273	945
Securities Available-For-Sale [Member]
Other Comprehensive Income (Loss) [Abstract]
Reclassification adjustment for net gains included in net gain on securities									(110)	(1,022)	(32)
Tax expense (benefit)									(50)	(461)	(14)
Net income									(60)	(561)	(18)
Change in net unrealized gain during the period, pre-tax									363	(2,441)	(1,335)
Change in net unrealized gain during the period, tax									162	(1,102)	(615)
Change in net unrealized gain during the period, after tax									201	(1,339)	(720)
Total securities available-for-sale, pre-tax									253	(3,463)	(1,367)
Total securities available-for-sale, tax									112	(1,563)	(629)
Total securities available-for-sale, after tax									141	(1,900)	(738)
Defined Benefit Plans [Member]
Other Comprehensive Income (Loss) [Abstract]
Reclassification adjustment for expense included in salaries and employee benefits expense									2,396	2,166	1,362
Tax expense (benefit)									1,082	978	615
Net income									1,314	1,188	747
Change in the net actuarial gain or loss, pre-tax									5,944	925	(7,859)
Change in the net actuarial gain or loss, tax									2,683	417	(3,548)
Change in the net actuarial gain or loss, after tax									3,261	508	(4,311)
Total defined benefit plans, pre-tax									8,340	3,091	(6,497)
Total defined benefit plans, tax									3,765	1,395	(2,933)
Total defined benefit plans, after tax									4,575	1,696	(3,564)
Total other comprehensive income, before tax									8,896	126	(6,144)
Total other comprehensive income, tax									4,015	57	(2,787)
Total other comprehensive income (loss), net of tax									$ 4,881	$ 69	$ (3,357)