Consolidated Statements of Equity - 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, 2016	$ 1,134,424	$ 5	$ 855,387	$ 273,704	$ 7	$ 5,321
Beginning balance, shares at Mar. 31, 2016		48,926,417
Exercise of stock options	12,117		12,117
Exercise of stock options, shares		273,050
Issuance of stock under Employee Stock Purchase Plan	10,286		10,286
Issuance of stock under Employee Stock Purchase Plan, shares		188,938
Common stock issued in public offering, net of issuance costs	503,061	$ 1	503,060
Common stock issued in public offering, net of issuance costs, shares		7,475,000
Stock-based compensation	62,397		62,397
Shares and fully-vested RSUs issued in settlement of certain accrued employee compensation liabilities, net of shares withheld for taxes which have been retired	13,080		13,080
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		176,731
RSU awards vesting, net of shares withheld for taxes which have been retired	(21,670)		(21,670)
RSU awards vesting, net of shares withheld for taxes which have been retired, shares		498,585
Shares issued in connection with acquisition of business	4,988		4,988
Shares issued in connection with acquisition of business, shares		61,888
Other noncontrolling interest activity	(8)					(8)
Net income (loss)	21,767			23,767		(2,000)
Other comprehensive income (loss), net of tax	(2,511)				(2,511)
Ending balance at Mar. 31, 2017	1,737,931	$ 6	1,439,645	297,471	(2,504)	3,313
Ending balance, shares at Mar. 31, 2017		57,600,609
Exercise of stock options	13,371		13,371
Exercise of stock options, shares		287,012
Issuance of stock under Employee Stock Purchase Plan	12,794		12,794
Issuance of stock under Employee Stock Purchase Plan, shares		227,381
Stock-based compensation	76,512		76,512
Shares and fully-vested RSUs issued in settlement of certain accrued employee compensation liabilities, net of shares withheld for taxes which have been retired	16,409		16,409
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		228,791
RSU awards vesting, net of shares withheld for taxes which have been retired	(24,206)		(24,206)
RSU awards vesting, net of shares withheld for taxes which have been retired, shares		561,481
Reclassification of stranded tax effects in OCI due toTax Reform Revaluation				(2,217)	2,217
Proceeds from noncontrolling interest capital contribution	8,491					8,491
Other noncontrolling interest activity	7					7
Net income (loss)	(68,275)			(67,305)		(970)
Other comprehensive income (loss), net of tax	15,852				15,852
Ending balance at Mar. 31, 2018	1,848,007	$ 6	1,535,635	285,960	15,565	10,841
Ending balance, shares at Mar. 31, 2018		58,905,274
Cumulative effect adjustment upon adoption of new stock compensation guidance (ASU 2016-09) | Accounting Standards Update 2016-09 [Member]	59,121		1,110	58,011
Exercise of stock options	11,087		11,087
Exercise of stock options, shares		275,000
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	91,470		91,470
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	(24,398)		(24,398)
RSU awards vesting, net of shares withheld for taxes which have been retired, shares		642,362
Other noncontrolling interest activity	(3,584)		81			(3,665)
Net income (loss)	(66,469)			(67,623)		1,154
Other comprehensive income (loss), net of tax	(10,227)				(10,227)
Ending balance at Mar. 31, 2019	1,916,078	$ 6	$ 1,656,819	245,585	$ 5,338	$ 8,330
Ending balance, shares at Mar. 31, 2019		60,550,093
Cumulative effect adjustment upon adoption of new revenue recognition guidance (ASU 2014-09) | Accounting Standards Update 2014-09 [Member]	$ 27,248			$ 27,248