SUMMARY OF ACCOUNTING POLICIES - Accounting Pronouncements (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Apr. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in investing activities	$ (908,985)	$ (702,187)	$ (1,396,376)
Decrease in operating activities	(753,598)	(1,149,909)	$ (1,136,445)
Accumulated deficit	(3,144,114)	(3,572,648)
Accounting Standards Update 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in operating activities	$ 1,900,000	$ 2,700,000
Subsequent Event | Minimum | Adjustment | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit				$ 30,000
Finished goods and work in progress inventory				300,000
Unbilled receivables				330,000
Subsequent Event | Maximum | Adjustment | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit				70,000
Finished goods and work in progress inventory				500,000
Unbilled receivables				$ 550,000