Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 1,460	$ 979	$ 2,535
Other comprehensive income, net of tax
Net unrealized losses on available-for-sale debt securities [net of tax benefit of $2, $10 and $8, respectively]	(7)	(37)	(28)
Reclassification of net (gains) losses realized on available-for-sale debt securities included in investment and other income, net [net of tax provision of $0, $0 and $0, respectively]	(1)	1	(1)
Other comprehensive loss	(8)	(36)	(29)
Comprehensive income	$ 1,452	$ 943	$ 2,506