PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS CHANGE IN PROJECTED BENEFIT OBLIGATION AND PLAN ASSETS (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair Value of Plan Assets, balance beginning of year			$ 2,156,148	$ 2,156,148
Defined Benefit Plan, Contributions by Employer				17,462	$ 20,020	$ 21,208
Fair Value of Plan Assets, balance end of year	$ 1,925,685			1,925,685	2,156,148
Accrued pension and other postretirement benefits, noncurrent	(664,664)			(664,664)	(538,381)
Other postretirement
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
PBO balance at beginning of year			239,267	239,267	311,012
Defined Benefit Plan, Service Cost				1,186	2,868	3,060
Defined Benefit Plan, Interest Cost				7,669	12,332	12,552
Defined Benefit Plan, Actuarial Gain (Loss)				2,030	(61,261)
Defined Benefit Plan, Business Combinations and Acquisitions, Benefit Obligation				0	0
Defined Benefit Plan, Plan Amendments				49,512	0
Defined Benefit Plan, Contributions by Plan Participants				2,323	3,339
Defined Benefit Plan, Special Termination Benefits				0	0	0
Defined Benefit Plan, Benefits Paid				(23,062)	(29,023)
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)				0	0
PBO balance at end of year	179,901			179,901	239,267	311,012
Defined Benefit Plan, Accumulated Benefit Obligation	$ 179,901			$ 179,901	$ 239,267
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.73%			3.73%	3.66%
Fair Value of Plan Assets, balance beginning of year			0	$ 0	$ 0
Defined Benefit Plan, Actual Return on Plan Assets				0	0
Defined Benefit Plan, Settlements, Plan Assets				0	0
Defined Benefit Plan, Contributions by Employer				20,739	25,684
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets				0	0
Defined Benefit Plan, Benefits Paid				(23,062)	(29,023)
Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets				0	0
Fair Value of Plan Assets, balance end of year	$ 0			0	0	0
Defined Benefit Plan, Funded Status of Plan	(179,901)			(179,901)	(239,267)
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent	0			0	0
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	(16,246)			(16,246)	(20,116)
Accrued pension and other postretirement benefits, noncurrent	(163,655)			(163,655)	(219,151)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	(47,384)			(47,384)	(8,682)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	(66,480)			(66,480)	(74,615)
Deferred Tax Assets, Other Comprehensive Loss	42,016			42,016	31,265
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(71,848)			(71,848)	(52,032)
Pension benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
PBO balance at beginning of year			2,479,319	2,479,319	2,160,708
Defined Benefit Plan, Service Cost				10,902	12,902	12,854
Defined Benefit Plan, Interest Cost				88,708	90,576	92,938
Defined Benefit Plan, Actuarial Gain (Loss)				37,342	341,719
Defined Benefit Plan, Business Combinations and Acquisitions, Benefit Obligation				0	39,575
Defined Benefit Plan, Plan Amendments	(2,297)	$ (3,314)	(2,863)	(7,395)	50
Defined Benefit Plan, Contributions by Plan Participants				212	145
Defined Benefit Plan, Special Termination Benefits				724	0	0
Defined Benefit Plan, Benefits Paid				(192,652)	(158,638)
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)				(1,635)	7,718
PBO balance at end of year	2,430,315			2,430,315	2,479,319	2,160,708
Defined Benefit Plan, Accumulated Benefit Obligation	2,419,305			$ 2,419,305	$ 2,464,418
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Range				3.25 - 3.93%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate					3.78%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligations, Rate of Compensation Increase Range				3.50 - 4.50%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase					3.50%
Fair Value of Plan Assets, balance beginning of year			$ 2,156,148	$ 2,156,148	$ 1,933,269
Defined Benefit Plan, Actual Return on Plan Assets				(39,482)	236,782
Defined Benefit Plan, Settlements, Plan Assets				0	0
Defined Benefit Plan, Contributions by Employer				3,021	112,338
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets				0	39,651
Defined Benefit Plan, Benefits Paid				(192,652)	(158,638)
Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets				(1,562)	(7,399)
Fair Value of Plan Assets, balance end of year	1,925,685			1,925,685	2,156,148	$ 1,933,269
Defined Benefit Plan, Funded Status of Plan	(504,630)			(504,630)	(323,171)
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent	0			0	0
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	(3,621)			(3,621)	(3,940)
Accrued pension and other postretirement benefits, noncurrent	(501,009)			(501,009)	(319,231)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	(6,755)			(6,755)	(20,155)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	569,435			569,435	340,034
Deferred Tax Assets, Other Comprehensive Loss	(205,406)			(205,406)	(118,445)
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	$ 357,274			$ 357,274	$ 201,434