CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (PARENTHETICAL) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 24,003	$ 22,120	$ 70,021	$ 106,089
Cost of Sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	3,494	3,468	10,587	15,465
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	10,921	9,881	31,797	37,569
Selling General And Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 9,588	$ 8,771	$ 27,637	$ 53,055