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) |