PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($)	1 Months Ended	3 Months Ended
	Jan. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Pension Benefits
Net periodic benefit cost [Abstract]
Service Cost		$ 1,315,000	$ 1,443,000
Interest Cost		3,000,000	2,770,000
Expected Return on Plan Assets		(3,380,000)	(3,699,000)
Amortizations:
Prior Service Cost		53,000	53,000
Actuarial Loss		2,309,000	2,656,000
Net Periodic Benefit Cost		3,297,000	3,223,000
Capitalized Benefit Cost		(1,187,000)	(1,239,000)
Deferred Benefit Cost		(161,000)	0
Total Net Periodic Benefit Expense		1,949,000	1,984,000
Contributions	$ 15,000,000	0
Estimated future contributions		0
Other Postretirement Benefits
Net periodic benefit cost [Abstract]
Service Cost		230,000	327,000
Interest Cost		653,000	771,000
Expected Return on Plan Assets		(776,000)	(748,000)
Amortizations:
Prior Service Cost		(86,000)	152,000
Actuarial Loss		294,000	384,000
Net Periodic Benefit Cost		315,000	886,000
Capitalized Benefit Cost		(101,000)	(256,000)
Total Net Periodic Benefit Expense		214,000	$ 630,000
Defined benefit plan regulatory obligation to contribute to the plan during the period		3,600,000
Supplemental Employee Retirement Plans, Defined Benefit
Amortizations:
Estimated future contributions		$ 2,300,000