Investments - Cost, Gross Unrealized Gains and Losses, and Fair Value of Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Mar. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	$ 708,840	$ 93,107
Gross Unrealized Gains	1	6
Gross Unrealized Losses	(5,361)	(27)
Fair Value	703,480	93,086
Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	22,981	16,946
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(1)
Fair Value	22,981	16,945
Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	685,859	76,161
Gross Unrealized Gains	1	6
Gross Unrealized Losses	(5,361)	(26)
Fair Value	680,499	76,141
Commercial paper \| Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		2,290
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		2,290
Corporate notes and bonds \| Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		3,517
Gross Unrealized Gains		0
Gross Unrealized Losses		(1)
Fair Value		3,516
Corporate notes and bonds \| Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	102,529	46,662
Gross Unrealized Gains	1	3
Gross Unrealized Losses	(343)	(24)
Fair Value	102,187	46,641
Money market funds \| Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	22,981	9,838
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	22,981	9,838
Certificates of deposit \| Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		1,301
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		1,301
Certificates of deposit \| Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	137	4,867
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Fair Value	137	4,868
Asset-backed securities \| Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	3,569	3,264
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4)	(1)
Fair Value	3,565	3,263
Commercial paper \| Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	2,656	16,411
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(3)	0
Fair Value	2,653	16,412
Sovereign bonds \| Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	8,775	1,100
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(84)	(1)
Fair Value	8,691	1,099
U.S. government and agency securities \| Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	568,193	3,857
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(4,927)	0
Fair Value	$ 563,266	$ 3,858

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

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Amortized cost excluding accrued interest, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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