COMMITMENTS AND CONTINGENCIES - Separation Programs (Details) - Involuntary separation program - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Severance costs	$ 2,727	$ 2,410	$ 4,446	$ 11,089
Direct cost
Restructuring Cost and Reserve [Line Items]
Severance costs	1,212	1,477	2,713	2,547
General and administrative
Restructuring Cost and Reserve [Line Items]
Severance costs	$ 1,515	$ 933	$ 1,733	$ 8,542

Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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