PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) (USD $)	1 Months Ended		3 Months Ended		6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pension Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost			$ 1,332,000	$ 1,078,000	$ 2,710,000	$ 2,267,000
Interest cost			2,387,000	2,412,000	4,719,000	4,811,000
Expected return on plan assets			(2,968,000)	(2,411,000)	(5,957,000)	(5,171,000)
Amortizations [Abstract]
Prior service cost (credits)			62,000	63,000	125,000	125,000
Actuarial loss			2,332,000	2,060,000	4,503,000	3,815,000
Net periodic benefit cost prior to ERIP and capitalized benefit costs			3,145,000	3,202,000	6,100,000	5,847,000
Capitalized benefit costs			(1,268,000)	(1,228,000)	(2,435,000)	(2,207,000)
Total net periodic benefit expense			1,877,000	1,974,000	3,665,000	3,640,000
Contributions	12,700,000	25,000,000
Other Postretirement Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost			259,000	225,000	570,000	518,000
Interest cost			665,000	733,000	1,365,000	1,501,000
Expected return on plan assets			(601,000)	(494,000)	(1,189,000)	(1,053,000)
Amortizations [Abstract]
Prior service cost (credits)			(71,000)	(71,000)	(142,000)	(142,000)
Actuarial loss			410,000	482,000	869,000	862,000
Net periodic benefit cost prior to ERIP and capitalized benefit costs			662,000	875,000	1,473,000	1,686,000
Capitalized benefit costs			(248,000)	(329,000)	(570,000)	(631,000)
Total net periodic benefit expense			414,000	546,000	903,000	1,055,000
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			$ 1,300,000		$ 1,300,000