Condensed Consolidated Statement of Equity (Unaudited) - 9 months ended Dec. 31, 2018 - USD ($) $ in Thousands	Total	Common Stock [Member]	Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest in Subsidiaries [Member]
Beginning balance at Mar. 31, 2018	$ 1,848,007	$ 6	$ 1,535,635	$ 285,960	$ 15,565	$ 10,841
Beginning balance, shares at Mar. 31, 2018		58,905,274
Exercise of stock options	8,352		8,352
Exercise of stock options, shares		225,000
Issuance of stock under Employee Stock Purchase Plan	15,243		15,243
Issuance of stock under Employee Stock Purchase Plan, shares		289,024
Stock-based compensation	67,109		67,109
Shares and fully-vested RSUs issued in settlement of certain accrued employee compensation liabilities, net of shares withheld for taxes which have been retired	27,701		27,701
Shares and fully-vested RSUs issued in settlement of certain accrued employee compensation liabilities, net of shares withheld for taxes which have been retired, shares		438,433
RSU awards vesting, net of shares withheld for taxes which have been retired	(23,680)		(23,680)
RSU awards vesting, net of shares withheld for taxes which have been retired, shares		622,532
Other noncontrolling interest activity	(3,584)		81			(3,665)
Net loss	(71,832)			(70,138)		(1,694)
Other comprehensive loss, net of tax	(8,518)				(8,518)
Ending balance at Dec. 31, 2018	1,886,046	$ 6	$ 1,630,441	243,070	$ 7,047	$ 5,482
Ending balance, shares at Dec. 31, 2018		60,480,263
Cumulative effect adjustment upon adoption of new revenue recognition guidance (ASU 2014-09) | Accounting Standards Update 2014-09 [Member]	$ 27,248			$ 27,248