RETIREMENT PLANS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Pension Plan [Member]
Components of net periodic benefit cost: [Abstract]
Service cost	$ 3,207	$ 2,552	$ 9,621	$ 7,657
Interest cost	2,851	2,627	8,553	7,881
Expected return on plan assets	(4,033)	(3,219)	(12,099)	(9,657)
Amortization of actuarial gain	2,070	1,850	6,209	5,548
Net periodic benefit cost	4,095	3,810	12,284	11,429
SERP [Member]
Components of net periodic benefit cost: [Abstract]
Service cost	0	0	0	0
Interest cost	18	18	53	55
Expected return on plan assets	0	0	0	0
Amortization of actuarial gain	5	4	14	11
Net periodic benefit cost	23	22	67	66
Other Postretirement Benefits [Member]
Components of net periodic benefit cost: [Abstract]
Service cost	0	0	0	0
Interest cost	27	34	83	101
Amortization of actuarial gain	(153)	(158)	(461)	(468)
Net periodic benefit cost	$ (126)	$ (124)	$ (378)	$ (367)