Net Recognized Gains (Losses) on Debt Investments (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2023
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Realized gains from sales of available-for-sale securities	$ 9	$ 4	$ 17	$ 6
Realized losses from sales of available-for-sale securities	(19)	(29)	(34)	(54)
Total	(860)	69	(397)	(38)
Debt Securities
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Impairments and allowance for credit losses	(14)	18	(2)	12
Total	$ (24)	$ (7)	$ (19)	$ (36)