SEGMENTS (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)
Financial information of reportable segment and the reconciliation of EBITDA to operating income
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component									$ (62,105)	$ (103,234)	$ (88,085)
Reporting Segments Number									3
Operating income (loss)	$ (189,197)	$ (16,933)	$ (2,001)	$ (66,548)	$ (310,437)	$ (154,206)	$ (29)	$ (968)	$ (274,679)	(465,640)	(31,196)
Interest Expense and Other									114,619	99,442	80,501
(Loss) income from continuing operations, before income taxes									(327,193)	(461,848)	(23,612)
Depreciation and amortization									149,904	158,368	176,946
Asset Impairment Charges					345,000	190,227			0	535,227	266,298
Amortization of Acquired Contract Liabilities									67,314	125,148	121,004
Adjusted EBITDA									130,453	133,548	310,168
Capital expenditures									47,099	42,050	51,832
Total assets	2,854,574				3,807,064				2,854,574	3,807,064
Revenues	869,027	807,895	855,108	832,900	896,860	775,246	745,156	781,689	3,364,930	3,198,951	3,532,799
Restructuring Charges									31,098	40,069	42,177
Gain (Loss) on Disposition of Business									(235,301)	(30,741)	(19,124)
Integrated Systems [Member]
Financial information of reportable segment and the reconciliation of EBITDA to operating income
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component										(1,804)	(1,085)
Operating income (loss)	42,394	39,947	39,866	35,409	54,562	42,216	41,641	46,982	157,615	185,401	200,209
Depreciation and amortization									29,052	35,986	40,332
Amortization of Acquired Contract Liabilities									34,121	38,293	36,760
Adjusted EBITDA									152,546	183,094	203,781
Capital expenditures									12,410	6,146	16,487
Total assets	1,215,350				1,225,770				1,215,350	1,225,770
Revenues	288,754	252,437	260,717	241,039	275,252	239,198	233,765	238,136	1,042,947	986,351	1,040,805
Aerospace Structures [Member]
Financial information of reportable segment and the reconciliation of EBITDA to operating income
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component										(75,708)	(87,000)
Operating income (loss)	(264)	(49,813)	(22,744)	(79,587)	(343,469)	(193,155)	(9,052)	(22,488)	(152,407)	(568,164)	(177,489)
Depreciation and amortization									111,431	113,786	126,116
Asset Impairment Charges									0	535,227	266,298
Amortization of Acquired Contract Liabilities									33,193	86,855	84,244
Adjusted EBITDA									13,072	(6,006)	130,681
Capital expenditures									30,581	29,519	30,434
Total assets	1,257,039				2,260,416				1,257,039	2,260,416
Revenues	511,314	490,337	528,367	532,387	550,371	473,273	447,771	483,314	2,062,404	1,954,729	2,172,768
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results				87,241
Product Support [Member]
Financial information of reportable segment and the reconciliation of EBITDA to operating income
Operating income (loss)	12,876	11,421	11,514	7,669	13,633	12,399	11,233	8,437	43,479	45,702	55,801
Depreciation and amortization									6,321	6,744	9,037
Amortization of Acquired Contract Liabilities										0
Adjusted EBITDA									49,800	52,446	64,838
Capital expenditures									3,324	2,206	2,630
Total assets	271,813				281,101				271,813	281,101
Revenues	73,883	71,446	72,199	66,215	79,075	68,039	68,366	66,433	283,743	281,913	338,325
Elimination of inter-segment sales
Financial information of reportable segment and the reconciliation of EBITDA to operating income
Operating income (loss)	(244,203)	(18,488)	(30,637)	(30,039)	(35,163)	(15,666)	(43,851)	(33,899)
Revenues	(4,924)	$ (6,325)	$ (6,175)	$ (6,741)	(7,838)	$ (5,264)	$ (4,746)	$ (6,194)	(24,164)	(24,042)	(19,099)
Corporate
Financial information of reportable segment and the reconciliation of EBITDA to operating income
Operating income (loss)									(323,366)	(128,579)	(109,717)
Depreciation and amortization									3,100	1,852	1,461
Adjusted EBITDA									(84,965)	(95,986)	(89,132)
Capital expenditures									784	4,179	2,281
Total assets	110,372				39,777				110,372	39,777
Parent
Financial information of reportable segment and the reconciliation of EBITDA to operating income
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component									264	(25,722)	0
Operating income (loss)									(323,216)	(154,594)	(109,603)
Interest Expense and Other									102,338	86,181	75,483
(Loss) income from continuing operations, before income taxes									(271,718)	(56,015)	(1,971)
Depreciation and amortization									3,099	1,851	1,461
Asset Impairment Charges										0	0
Capital expenditures									784	4,179	2,281
Total assets	1,240,500				2,040,756				1,240,500	2,040,756
Revenues									0	0	0
Restructuring Charges									6,233	19,269	22,196
Gain (Loss) on Disposition of Business									(234,963)	(30,741)
Sales [Member]
Financial information of reportable segment and the reconciliation of EBITDA to operating income
Revenues									960,299	758,936	$ 768,703
Assets [Member]
Financial information of reportable segment and the reconciliation of EBITDA to operating income
Disclosure on Geographic Areas, Long-Lived Assets in Foreign Countries	$ 294,990				$ 222,841				$ 294,990	$ 222,841