Condensed Consolidated Statements of Equity (Unaudited) - 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
Cumulative effect adjustment upon adoption of new revenue recognition guidance (ASU 2014-09) | Accounting Standards Update 2014-09 [Member]	27,248			27,248
Other noncontrolling interest activity	(3,584)		81			(3,665)
Net (loss) income	(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
Beginning balance at Sep. 30, 2018	1,884,337	$ 6	1,614,224	252,107	8,376	9,624
Beginning balance, shares at Sep. 30, 2018		59,650,229
Exercise of stock options	4,649		4,649
Exercise of stock options, shares		124,000
Issuance of stock under Employee Stock Purchase Plan	7,859		7,859
Issuance of stock under Employee Stock Purchase Plan, shares		156,844
Stock-based compensation	23,164		23,164
RSU awards vesting, net of shares withheld for taxes which have been retired	(21,557)		(21,557)
RSU awards vesting, net of shares withheld for taxes which have been retired, shares		549,190
Cumulative effect adjustment upon adoption of new revenue recognition guidance (ASU 2014-09) | Accounting Standards Update 2014-09 [Member]	1,367			1,367
Other noncontrolling interest activity	(1,707)		2,102			(3,809)
Net (loss) income	(10,737)			(10,404)		(333)
Other comprehensive loss, net of tax	(1,329)				(1,329)
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
Beginning balance at Mar. 31, 2019	1,916,078	$ 6	1,656,819	245,585	5,338	8,330
Beginning balance, shares at Mar. 31, 2019		60,550,093
Exercise of stock options	20,743		20,743
Exercise of stock options, shares		335,373
Issuance of stock under Employee Stock Purchase Plan	17,350		17,350
Issuance of stock under Employee Stock Purchase Plan, shares		311,137
Stock-based compensation	73,523		73,523
Shares and fully-vested RSUs issued in settlement of certain accrued employee compensation liabilities, net of shares withheld for taxes which have been retired	22,829		22,829
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		255,615
RSU awards vesting, net of shares withheld for taxes which have been retired	(28,268)		(28,268)
RSU awards vesting, net of shares withheld for taxes which have been retired, shares		671,040
Net (loss) income	8,915			(1,798)		10,713
Other comprehensive loss, net of tax	(5,859)				(5,859)
Ending balance at Dec. 31, 2019	2,025,311	$ 6	1,762,996	243,787	(521)	19,043
Ending balance, shares at Dec. 31, 2019		62,123,258
Beginning balance at Sep. 30, 2019	2,005,836	$ 6	1,751,924	237,311	1,666	14,929
Beginning balance, shares at Sep. 30, 2019		61,352,560
Exercise of stock options	2,033		2,033
Exercise of stock options, shares		33,642
Issuance of stock under Employee Stock Purchase Plan	9,044		9,044
Issuance of stock under Employee Stock Purchase Plan, shares		145,367
Stock-based compensation	25,135		25,135
RSU awards vesting, net of shares withheld for taxes which have been retired	(25,140)		(25,140)
RSU awards vesting, net of shares withheld for taxes which have been retired, shares		591,689
Net (loss) income	10,590			6,476		4,114
Other comprehensive loss, net of tax	(2,187)				(2,187)
Ending balance at Dec. 31, 2019	$ 2,025,311	$ 6	$ 1,762,996	$ 243,787	$ (521)	$ 19,043
Ending balance, shares at Dec. 31, 2019		62,123,258