Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2021
Statement Of Income And Comprehensive Income [Abstract]
Net unrealized gains on available-for-sale marketable securities, tax benefit (provision)	$ 0	$ 1	$ 14	$ (1)
Reclassification adjustment for net losses available-for-sale marketable securities included in investment and other income, tax provision (benefit)	$ 0	$ 0	$ 0	$ 0

Amount, before adjustment, of tax expense (benefit) for unrealized holding gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Excludes tax expense (benefit) for unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI https://asc.fasb.org/extlink&oid=126968391&loc=d3e640-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (f)
-URI https://asc.fasb.org/extlink&oid=126968391&loc=SL7669646-108580

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration