PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2010	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Pension Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost		$ 946,000	$ 854,000	$ 1,959,000	$ 1,713,000
Interest cost		2,404,000	2,338,000	4,762,000	4,599,000
Expected return on plan assets		(2,340,000)	(2,258,000)	(4,684,000)	(4,201,000)
Amortizations [Abstract]
Prior service cost (credits)		66,000	78,000	133,000	140,000
Actuarial loss		1,417,000	999,000	2,720,000	2,375,000
Net periodic benefit cost prior to ERIP and capitalized benefit costs		2,493,000	2,011,000	4,890,000	4,626,000
Defined benefit plan ERIP Costs		0	0	102,000	0
Capitalized benefit costs		(902,000)	(766,000)	(1,812,000)	(1,754,000)
Total net periodic benefit expense		1,591,000	1,245,000	3,180,000	2,872,000
Contributions	8,000,000
Other Postretirement Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost		228,000	221,000	498,000	460,000
Interest cost		820,000	813,000	1,600,000	1,634,000
Expected return on plan assets		(562,000)	(564,000)	(1,124,000)	(969,000)
Amortizations [Abstract]
Prior service cost (credits)		(88,000)	(89,000)	(177,000)	(177,000)
Actuarial loss		434,000	291,000	827,000	747,000
Net periodic benefit cost prior to ERIP and capitalized benefit costs		832,000	672,000	1,624,000	1,695,000
Capitalized benefit costs		(297,000)	(240,000)	(605,000)	(659,000)
Total net periodic benefit expense		535,000	432,000	1,019,000	1,036,000
Defined benefit plan regulatory obligation to contribute to the plan during the period		$ 3,600,000		$ 3,600,000