Borrowings - Long-Term Debt, Debt Issued (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | |
|---|---|---|---|
Mar. 31, 2020 |
Jun. 30, 2020 |
Jun. 30, 2019 |
|
| Long-term Debt Instrument | |||
| Notes Issued | |||
| Aggregate amount of debt issued | $ 20,000 | ||
| U.S dollar. fixed and floating rate notes | |||
| Notes Issued | |||
| Aggregate amount of debt issued | 20,000 | ||
| U.S dollar. fixed rate notes | |||
| Notes Issued | |||
| Aggregate amount of debt issued | $ 4,000 | ||
| Euro fixed-rate notes | |||
| Notes Issued | |||
| Aggregate amount of debt issued | 4,100 | $ 5,700 | |
| Fixed rate debt due in 2021 | |||
| Notes Issued | |||
| Outstanding debt redeemed | $ 2,900 | ||
| Loss upon redemption on notes | $ (49) |