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, 2015		(104,594)		(16,238)
Balance at Mar. 31, 2015	$ 563,088	$ 1,046	$ 1,028,197	$ (276,836)	$ (158,695)	$ (30,624)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(8,302)				(8,302)
Change in cumulative foreign currency translation adjustment	(7,364)					(7,364)
Change in unrealized gains on derivative instruments, net	(17)					(17)
Net unrealized gain on available-for-sale securities, net of taxes	109					109
Stock-based compensation	83,137		83,137
Tax benefit associated with stock awards	1,421		1,421
Issuance of restricted stock, net of forfeitures and cancellations (in shares)		(84)
Issuance of restricted stock, net of forfeitures and cancellations	0	$ (1)	1
Repurchased common stock (in shares)				(954)
Repurchased common stock	(26,552)			$ (26,552)
Net share settlement of restricted stock awards (in shares)		(745)
Net share settlement of restricted stock awards	(24,135)	$ (7)	(24,128)
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 (loss)	67,303				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
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)	(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 (loss)	173,533				173,533
Change in cumulative foreign currency translation adjustment	43,379					43,379
Change in unrealized gains on derivative instruments, 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)
Repurchased common stock (in shares)				(1,513)
Repurchased common stock	(154,792)			$ (154,792)
Settlement/Conversion of Convertible Notes (in shares)											12,082
Conversion of Convertible Notes										$ 255,084	$ 121	$ 254,963
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
Adoption of ASU 2016-09	$ (323)