PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Benefits [Member]
Net periodic benefit cost [Abstract]
Service Cost	$ 4,533	$ 3,918	$ 3,426
Interest Cost	9,622	9,524	9,197
Expected Return on Plan Assets	(10,341)	(9,367)	(8,402)
Amortizations [Abstract]
Prior Service Cost (Credits)	251	267	280
Actuarial Loss	7,629	5,440	4,751
Net Periodic Benefit Cost Prior to ERIP and Capitalized Benefit Costs	11,694	9,782	9,252
ERIP Costs	0	102	0
Capitalized Benefit Costs	(4,684)	(3,661)	(3,445)
Total Net Periodic Benefit Expense	7,010	6,223	5,807
Other Postretirement Benefits [Member]
Net periodic benefit cost [Abstract]
Service Cost	1,037	996	920
Interest Cost	3,001	3,201	3,267
Expected Return on Plan Assets	(2,105)	(2,248)	(1,937)
Amortizations [Abstract]
Prior Service Cost (Credits)	(283)	(355)	(355)
Actuarial Loss	1,725	1,654	1,495
Net Periodic Benefit Cost Prior to ERIP and Capitalized Benefit Costs	3,375	3,248	3,390
Capitalized Benefit Costs	(1,340)	(1,222)	(1,295)
Total Net Periodic Benefit Expense	$ 2,035	$ 2,026	$ 2,095