Net Recognized Gains (Losses) on Debt Investments (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Jun. 30, 2019 |
Jun. 30, 2018 |
Jun. 30, 2017 |
|
| 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 | $ 12 | $ 27 | $ 108 |
| Realized losses from sales of available-for-sale securities | (93) | (987) | (162) |
| Total | 648 | 2,399 | 2,583 |
| Debt Securities | |||
| Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items] | |||
| Other-than-temporary impairments of investments | (16) | (6) | (14) |
| Total | $ (97) | $ (966) | $ (68) |