Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 748	$ 668	$ 2,291	$ 1,697
Other comprehensive income, net of tax
Net unrealized (losses) gains on available-for-sale marketable securities [net of tax benefit (provision) of $1, $0, ($1) and ($6), respectively]	(3)	2	4	26
Reclassification adjustment for net gains on available-for-sale marketable securities included in investment and other income, net [net of tax provision of $0, $0, $0 and $4, respectively]	(1)	(2)	(1)	(15)
Other comprehensive (loss) income	(4)	0	3	11
Comprehensive income	$ 744	$ 668	$ 2,294	$ 1,708