CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings/(Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	1.75% Convertible Notes due 2016	1.75% Convertible Notes due 2016 Common Stock	1.75% Convertible Notes due 2016 Additional Paid-in Capital	1.00% Convertible Notes due 2018	1.00% Convertible Notes due 2018 Common Stock	1.00% Convertible Notes due 2018 Additional Paid-in Capital
Balance (in shares) at Mar. 31, 2016			103,765		17,192
Balance at Mar. 31, 2016	$ 581,385		$ 1,038	$ 1,088,628	$ (303,388)	$ (166,997)	$ (37,896)
Increase (Decrease) in Stockholders' Equity
Net income	67,303	[1]				67,303
Change in cumulative foreign currency translation adjustment	(9,086)						(9,086)
Net unrealized gain on available-for-sale securities, net of taxes	(160)						(160)
Stock-based compensation	88,378			88,378
Tax benefit associated with stock awards	1,990			1,990
Issuance of restricted stock, net of forfeitures and cancellations (in shares)			(1,738)
Issuance of restricted stock, net of forfeitures and cancellations	0		$ 17	(17)
Settlement/Conversion of Convertible Notes (in shares)									13,094			899
Settlement/Conversion of Convertible Notes								$ 249,997	$ 131	$ 249,866	$ 18,341	$ 9	$ 18,332
Issuance of shares related to Social Point acquisition (in shares)			1,480
Issuance of shares related to Social Point acquisition	57,342		$ 15	57,327
Net share settlement of restricted stock awards (in shares)			(1,163)
Net share settlement of restricted stock awards	(51,762)		$ (12)	(51,750)
Balance (in shares) at Mar. 31, 2017			119,813		17,192
Balance at Mar. 31, 2017	1,003,728		$ 1,198	1,452,754	$ (303,388)	(99,694)	(47,142)
Increase (Decrease) in Stockholders' Equity
Net income	173,533	[1]				173,533
Change in cumulative foreign currency translation adjustment	43,379						43,379
Change in unrealized gains on cash flow hedge, net	(10,191)						(10,191)
Net unrealized gain on available-for-sale securities, net of taxes	(1,778)						(1,778)
Stock-based compensation	293,214			293,214
Issuance of restricted stock, net of forfeitures and cancellations (in shares)			(2,151)
Issuance of restricted stock, net of forfeitures and cancellations	0		$ 21	(21)
Settlement/Conversion of Convertible Notes (in shares)												12,082
Settlement/Conversion of Convertible Notes											255,084	$ 121	254,963
Repurchased common stock (in shares)					(1,513)
Repurchased common stock	(154,792)				$ (154,792)
Net share settlement of restricted stock awards (in shares)			(1,303)
Net share settlement of restricted stock awards	$ (112,884)		$ (13)	(112,871)
Balance (in shares) at Mar. 31, 2018	132,743		132,743		18,705
Balance at Mar. 31, 2018	$ 1,488,970		$ 1,327	1,888,039	$ (458,180)	73,516	(15,732)
Increase (Decrease) in Stockholders' Equity
Net income	333,837					333,837
Change in cumulative foreign currency translation adjustment	(33,456)						(33,456)
Change in cumulative foreign currency translation adjustment	(28,803)
Change in unrealized gains on cash flow hedge, net	4,906						4,906
Net unrealized gain on available-for-sale securities, net of taxes	2,440						2,440
Stock-based compensation	219,460			219,460
Issuance of restricted stock, net of forfeitures and cancellations (in shares)			(2,345)
Issuance of restricted stock, net of forfeitures and cancellations	0		$ 23	(23)
Settlement/Conversion of Convertible Notes (in shares)												377
Settlement/Conversion of Convertible Notes											$ 8,112	$ 4	$ 8,108
Repurchased common stock (in shares)					(3,716)
Repurchased common stock	(362,392)				$ (362,392)
Net share settlement of restricted stock awards (in shares)			(920)
Net share settlement of restricted stock awards	(101,293)		$ (9)	(101,284)
Employee share purchase plan settlement (in shares)			57
Employee share purchase plan settlement	$ 5,070		$ 1	5,069
Balance (in shares) at Mar. 31, 2019	134,602		134,602		22,421
Balance at Mar. 31, 2019	$ 2,040,580		$ 1,346	$ 2,019,369	$ (820,572)	$ 877,626	$ (37,189)

[1] Prior period amounts have been adjusted retrospectively to reflect the adoption of ASU 2016-18, Statement of Cash Flows (Topic 230): RestrictedCash. Refer to Note 1 for further discussion.