CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling interest
Beginning balance (in shares) at Mar. 31, 2020		135,927		(22,421)
Beginning 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
Net income	187,826				187,826
Change in cumulative foreign currency translation adjustment	23,562					23,562
Change in gains on cash flow hedge, net	(4,305)					(4,305)
Net unrealized gain on available-for-sale securities, net of taxes	4,295					4,295
Stock-based compensation	94,712		94,712
Issuance of restricted stock, net of forfeitures and cancellations (in shares)		1,094
Issuance of restricted stock, net of forfeitures and cancellations	0	$ 11	(11)
Net share settlement of restricted stock awards (in shares)		(341)
Net share settlement of restricted stock awards	(48,202)	$ (4)	(48,198)
Employee share purchase plan settlement (in shares)		65
Employee share purchase plan settlement	6,503	$ 1	6,502
Issuance of shares related to acquisition (in shares)		604
Issuance of shares related to acquisition	97,647	$ 6	97,641
Ending balance (in shares) at Sep. 30, 2020		137,349		(22,421)
Ending balance at Sep. 30, 2020	2,901,282	$ 1,373	2,285,394	$ (820,572)	1,469,911	(34,824)
Beginning balance (in shares) at Jun. 30, 2020		136,689		(22,421)
Beginning balance at Jun. 30, 2020	2,651,028	$ 1,367	2,151,774	$ (820,572)	1,370,590	(52,131)
Increase (Decrease) in Stockholders' Equity
Net income	99,321				99,321
Change in cumulative foreign currency translation adjustment	18,861					18,861
Net unrealized gain on available-for-sale securities, net of taxes	(1,554)					(1,554)
Stock-based compensation	45,675		45,675
Issuance of restricted stock, net of forfeitures and cancellations (in shares)		115
Issuance of restricted stock, net of forfeitures and cancellations	0	$ 1	(1)
Net share settlement of restricted stock awards (in shares)		(59)
Net share settlement of restricted stock awards	(9,696)	$ (1)	(9,695)
Issuance of shares related to acquisition (in shares)		604
Issuance of shares related to acquisition	97,647	$ 6	97,641
Ending balance (in shares) at Sep. 30, 2020		137,349		(22,421)
Ending balance at Sep. 30, 2020	2,901,282	$ 1,373	2,285,394	$ (820,572)	1,469,911	(34,824)
Beginning balance (in shares) at Mar. 31, 2021		137,584		(22,421)
Beginning 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
Net income	162,553				162,553
Change in cumulative foreign currency translation adjustment	(10,599)					(10,599)
Net unrealized gain on available-for-sale securities, net of taxes	(484)					(484)
Stock-based compensation	136,304		136,304
Repurchased common stock (in shares)				(1,260)
Repurchased common stock	(200,012)			$ (200,012)
Issuance of restricted stock, net of forfeitures and cancellations (in shares)		1,020
Issuance of restricted stock, net of forfeitures and cancellations	0	$ 10	(10)
Net share settlement of restricted stock awards (in shares)		(298)
Net share settlement of restricted stock awards	(53,370)	$ (2)	(53,368)
Employee share purchase plan settlement (in shares)		70
Employee share purchase plan settlement	9,230	$ 1	9,229
Issuance of shares related to acquisition (in shares)		515
Issuance of shares related to acquisition	94,154	$ 5	94,149
Ending balance (in shares) at Sep. 30, 2021		138,891		(23,681)
Ending balance at Sep. 30, 2021	3,469,668	$ 1,390	2,475,085	$ (1,020,584)	2,033,524	(19,747)	$ 0
Beginning balance (in shares) at Jun. 30, 2021		138,846		(22,421)
Beginning balance at Jun. 30, 2021	3,631,307	$ 1,389	2,417,658	$ (820,572)	2,023,227	(2,770)	12,375
Increase (Decrease) in Stockholders' Equity
Net income	10,297				10,297
Change in cumulative foreign currency translation adjustment	(16,731)					(16,731)
Net unrealized gain on available-for-sale securities, net of taxes	(246)					(246)
Stock-based compensation	62,537		62,537
Repurchased common stock (in shares)				(1,260)
Repurchased common stock	(200,012)			$ (200,012)
Issuance of restricted stock, net of forfeitures and cancellations (in shares)		77
Issuance of restricted stock, net of forfeitures and cancellations	0	$ 1	(1)
Net share settlement of restricted stock awards (in shares)		(32)
Net share settlement of restricted stock awards	(5,109)	$ 0	(5,109)
Call option related to Nordeus Acquisition	(12,375)						(12,375)
Ending balance (in shares) at Sep. 30, 2021		138,891		(23,681)
Ending balance at Sep. 30, 2021	$ 3,469,668	$ 1,390	$ 2,475,085	$ (1,020,584)	$ 2,033,524	$ (19,747)	$ 0