Net Recognized Gains (Losses) on Equity Investments (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Jun. 30, 2020 |
Jun. 30, 2019 |
Jun. 30, 2018 |
|
| Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items] | |||
| Net realized gains on investments sold | $ 83 | $ 276 | $ 3,406 |
| Net unrealized gains on investments still held | 69 | 479 | 0 |
| Total | 32 | 648 | 2,399 |
| Equity 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 | (116) | (10) | (41) |
| Total | $ 36 | $ 745 | $ 3,365 |