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)
Beginning balance (in shares) at Mar. 31, 2019		134,602		(22,421)
Beginning balance at Mar. 31, 2019	$ 2,040,580	$ 1,346	$ 2,019,369	$ (820,572)	$ 877,626	$ (37,189)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	404,459				404,459
Change in cumulative foreign currency translation adjustment	(27,445)					(27,445)
Net unrealized gain on available-for-sale securities, net of taxes	(3,332)					(3,332)
Change in unrealized gains on cash flow hedge, net	9,590					9,590
Stock-based compensation	192,845		192,845
Issuance of restricted stock, net of forfeitures and cancellations (in shares)		1,970
Issuance of restricted stock, net of forfeitures and cancellations	0	$ 19	(19)
Net share settlement of restricted stock awards (in shares)		(771)
Net share settlement of restricted stock awards	(87,968)	$ (8)	(87,960)
Employee share purchase plan settlement (in shares)		126
Employee share purchase plan settlement	10,515	$ 2	10,513
Ending balance (in shares) at Mar. 31, 2020		135,927		(22,421)
Ending balance at Mar. 31, 2020	2,539,244	$ 1,359	2,134,748	$ (820,572)	1,282,085	(58,376)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	588,886				588,886
Change in cumulative foreign currency translation adjustment	51,253					51,253
Net unrealized gain on available-for-sale securities, net of taxes	3,364					3,364
Change in unrealized gains on cash flow hedge, net	(4,905)					(4,905)
Stock-based compensation	113,741		113,741
Issuance of restricted stock, net of forfeitures and cancellations (in shares)		1,376
Issuance of restricted stock, net of forfeitures and cancellations	0	$ 13	(13)
Net share settlement of restricted stock awards (in shares)		(462)
Net share settlement of restricted stock awards	(71,552)	$ (4)	(71,548)
Employee share purchase plan settlement (in shares)		139
Employee share purchase plan settlement	14,214	$ 2	14,212
Issuance of shares (in shares)		604
Issuance of shared	97,647	$ 6	97,641
Ending balance (in shares) at Mar. 31, 2021		137,584		(22,421)
Ending balance at Mar. 31, 2021	3,331,892	$ 1,376	2,288,781	$ (820,572)	1,870,971	(8,664)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	418,022				418,022
Change in cumulative foreign currency translation adjustment	(43,589)					(43,589)
Net unrealized gain on available-for-sale securities, net of taxes	(5,092)					(5,092)
Repurchased common stock (in shares)				(1,260)
Repurchased common stock	(200,012)			$ (200,012)
Stock-based compensation	258,701		258,701
Issuance of restricted stock, net of forfeitures and cancellations (in shares)		1,168
Issuance of restricted stock, net of forfeitures and cancellations	0	$ 12	(12)
Net share settlement of restricted stock awards (in shares)		(362)
Net share settlement of restricted stock awards	(64,074)	$ (4)	(64,070)
Employee share purchase plan settlement (in shares)		143
Employee share purchase plan settlement	19,657	$ 1	19,656
Issuance of shares (in shares)		515
Issuance of shared	94,154	$ 5	94,149
Ending balance (in shares) at Mar. 31, 2022		139,048		(23,681)
Ending balance at Mar. 31, 2022	$ 3,809,659	$ 1,390	$ 2,597,205	$ (1,020,584)	$ 2,288,993	$ (57,345)