Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 603	$ 364	$ 1,318	$ 653
Other comprehensive income, net of tax
Net unrealized gains (losses) on available-for-sale debt securities [net of tax (provision) benefit of ($8), $0, $0 and $14, respectively]	30	3	1	(48)
Reclassification of net (losses) gains realized on available-for sale debt securities included in investment and other income, net [net of tax provision of $0, $0, $0 and $0, respectively]	0	0	(1)	2
Other comprehensive income (loss)	30	3	0	(46)
Comprehensive income	$ 633	$ 367	$ 1,318	$ 607