PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 31, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Pension Benefits
Net periodic benefit cost [Abstract]
Service Cost		$ 1,334,000	$ 813,000	$ 4,003,000	$ 3,383,000
Interest Cost		2,792,000	2,661,000	8,376,000	8,051,000
Expected Return on Plan Assets		(3,697,000)	(3,262,000)	(11,092,000)	(9,792,000)
Amortizations:
Prior Service Cost		53,000	45,000	159,000	131,000
Actuarial Loss		2,652,000	1,398,000	7,956,000	4,250,000
Net Periodic Benefit Cost		3,134,000	1,655,000	9,402,000	6,023,000
Capitalized Benefit Cost		(1,216,000)	(577,000)	(3,649,000)	(2,285,000)
Deferred Benefit Cost		(341,000)	0	(666,000)	0
Total Net Periodic Benefit Expense		1,577,000	1,078,000	5,087,000	3,738,000
Contributions	$ 15,000,000					$ 0
Other Postretirement Benefits
Net periodic benefit cost [Abstract]
Service Cost		279,000	168,000	837,000	668,000
Interest Cost		743,000	659,000	2,230,000	2,139,000
Expected Return on Plan Assets		(748,000)	(688,000)	(2,245,000)	(2,062,000)
Amortizations:
Prior Service Cost		152,000	38,000	456,000	114,000
Actuarial Loss		336,000	245,000	1,007,000	731,000
Net Periodic Benefit Cost		762,000	422,000	2,285,000	1,590,000
Capitalized Benefit Cost		(264,000)	(42,000)	(792,000)	(460,000)
Deferred Benefit Cost		(89,000)	0	(168,000)	0
Total Net Periodic Benefit Expense		$ 409,000	$ 380,000	1,325,000	$ 1,130,000
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				$ 1,500,000