Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2025	Dec. 31, 2024
Statement of Comprehensive Income [Abstract]
Net income	$ 479	$ 429	$ 1,896	$ 1,215
Other comprehensive income, net of tax
Net unrealized gains (losses) on available-for-sale debt securities [net of tax benefit (provision) of $0, $6, ($2) and $1, respectively]	1	(21)	9	(4)
Reclassification of net gains realized on available-for-sale debt securities included in investment and other income, net [net of tax benefit (provision) of $0, $0, $0 and ($1), respectively]	0	0	1	2
Other comprehensive income (loss)	1	(21)	10	(2)
Comprehensive income	$ 480	$ 408	$ 1,906	$ 1,213