PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Pension Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost		$ 873,000	$ 741,000	$ 2,619,000	$ 2,222,000
Interest cost		1,853,000	1,800,000	5,559,000	5,401,000
Expected return on plan assets		(1,991,000)	(1,771,000)	(5,974,000)	(5,312,000)
Amortizations [Abstract]
Prior service cost (credits)		48,000	51,000	145,000	151,000
Actuarial loss		1,469,000	1,028,000	4,407,000	3,085,000
Net periodic benefit cost prior to capitalized benefit costs		2,252,000	1,849,000	6,756,000	5,547,000
Capitalized benefit costs		(1,306,000)	(906,000)	(3,513,000)	(2,718,000)
Total net periodic benefit expense		946,000	943,000	3,243,000	2,829,000
Contributions	19,800,000
Other Postretirement Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost		198,000	189,000	594,000	568,000
Interest cost		573,000	608,000	1,719,000	1,824,000
Expected return on plan assets		(402,000)	(427,000)	(1,206,000)	(1,281,000)
Amortizations [Abstract]
Prior service cost (credits)		(54,000)	(67,000)	(162,000)	(202,000)
Actuarial loss		329,000	314,000	988,000	942,000
Net periodic benefit cost prior to capitalized benefit costs		644,000	617,000	1,933,000	1,851,000
Capitalized benefit costs		(374,000)	(302,000)	(1,005,000)	(907,000)
Total net periodic benefit expense		270,000	315,000	928,000	944,000
Defined benefit plan regulatory obligation to contribute to the plan during the period		3,600,000		3,600,000
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Amortizations [Abstract]
Estimated future contributions		$ 1,200,000		$ 1,200,000