DISCONTINUED OPERATIONS - Narrative (Details)		3 Months Ended		6 Months Ended		12 Months Ended
	Feb. 06, 2018 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2008 unit	Sep. 30, 2017 USD ($)	Sep. 05, 2017 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue		$ 0	$ 0	$ 0	$ 0
Number of units sold | unit						11
Number of closed units | unit						1
Number of merged units | unit						2
Environmental exit costs, costs accrued to date							$ 5,700,000
PPC [Member] | Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue		45,832,000	111,958,000	166,262,000	$ 226,780,000
Consideration								$ 475,000,000
Gain on sale of business	$ 117,625,000	117,625,000	$ 0	117,625,000
Gain on sale of business net of tax	86,357,000
Accrued taxes payable		$ 46,968,000		$ 46,968,000
Plastics [Member] | Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration	$ 475,000,000