DEBT - INTEREST EXPENSE COMPONENTS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017		Jun. 18, 2013
Debt Instrument [Line Items]
Non-cash amortization of discount on Convertible Notes			$ 91	$ 15,424	[1]
Amortization of debt issuance costs			88	554	[1]
Convertible Debt | 1.00% Convertible Notes due 2018
Debt Instrument [Line Items]
Interest rate						1.00%
Cash interest expense (coupon interest expense)	$ 0	$ (60)	1	519
Non-cash amortization of discount on Convertible Notes	0	1,509	91	15,424
Amortization of debt issuance costs	0	48	3	471
Total interest expense related to Convertible Notes	$ 0	$ 1,497	$ 95	$ 16,414

[1] Prior period amounts have been adjusted retrospectively to reflect the adoption of ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. Refer to Note 1 for further discussion.