PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) (USD $)	1 Months Ended		3 Months Ended		9 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Pension Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost			$ 1,040,000	$ 873,000	$ 3,120,000	$ 2,619,000
Interest cost			1,811,000	1,853,000	5,434,000	5,559,000
Expected return on plan assets			(2,286,000)	(1,991,000)	(6,859,000)	(5,974,000)
Amortizations [Abstract]
Prior service cost (credits)			48,000	48,000	144,000	145,000
Actuarial loss			1,729,000	1,469,000	5,185,000	4,407,000
Net periodic benefit cost prior to capitalized benefit costs			2,342,000	2,252,000	7,024,000	6,756,000
Capitalized benefit costs			(1,218,000)	(1,306,000)	(3,653,000)	(3,513,000)
Total net periodic benefit expense			1,124,000	946,000	3,371,000	3,243,000
Contributions	9,100,000	19,800,000
Other Postretirement Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost			212,000	198,000	637,000	594,000
Interest cost			509,000	573,000	1,526,000	1,719,000
Expected return on plan assets			(443,000)	(402,000)	(1,329,000)	(1,206,000)
Amortizations [Abstract]
Prior service cost (credits)			(53,000)	(54,000)	(159,000)	(162,000)
Actuarial loss			324,000	329,000	972,000	988,000
Net periodic benefit cost prior to capitalized benefit costs			549,000	644,000	1,647,000	1,933,000
Capitalized benefit costs			(285,000)	(374,000)	(856,000)	(1,005,000)
Total net periodic benefit expense			264,000	270,000	791,000	928,000
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