Borrowings Borrowings - Senior Unsecured (Details) - Subsidiaries [Member] - Senior unsecured notes - USD ($) $ in Millions |
Jul. 25, 2019 |
Mar. 19, 2019 |
|---|---|---|
| Fixed Rate Senior Notes Due 2024 [Member] | ||
| Debt Instrument [Line Items] | ||
| Principal amount | $ 600 | |
| Stated interest rate | 4.375% | |
| Fixed Rate Senior Notes Due 2029 [Member] | ||
| Debt Instrument [Line Items] | ||
| Principal amount | $ 650 | |
| Stated interest rate | 5.15% | |
| Fixed Rate Senior Notes Due 2022 [Member] | ||
| Debt Instrument [Line Items] | ||
| Principal amount | $ 750 | |
| Stated interest rate | 2.85% |