Gains (Losses) on Fair Value Hedges and Related Hedged Items (Detail) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Foreign Exchange Contracts | ||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Derivatives | $ 14 | $ 685 | $ 36 | $ 637 |
| Hedged items | 12 | (674) | 10 | (606) |
| Total amount of ineffectiveness | 26 | 11 | 46 | 31 |
| Equity Contracts | ||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Derivatives | (71) | (7) | (307) | (17) |
| Hedged items | 71 | 7 | 307 | 17 |
| Total amount of ineffectiveness | 0 | 0 | 0 | 0 |
| Amount of equity contracts excluded from effectiveness assessment | $ 20 | $ (1) | $ 60 | $ (4) |