Long-Term Debt and Short-Term Borrowings - Floating Rate Notes (Details) - USD ($) $ in Millions |
1 Months Ended | 12 Months Ended |
|---|---|---|
Dec. 31, 2004 |
Dec. 31, 2018 |
|
| Floating rate notes due 2027 and 2040 and 2041 | ||
| Number of years after date of issuance that put options commence | 10 years | |
| Number of years after put options commence when additional put options occur on each anniversary thereafter until final maturity | 3 years | |
| Floating rate note due 2044 | ||
| Debt Instrument Term | 40 years | |
| Debt Instrument, Face Amount | $ 60 | $ 55 |
| Repurchase price of floating rate notes (as a percent) | 100.00% | |
| Maximum | Floating rate notes due 2027 and 2040 and 2041 | ||
| Repurchase price of floating rate notes (as a percent) | 100.00% | |
| Minimum | Floating rate notes due 2027 and 2040 and 2041 | ||
| Repurchase price of floating rate notes (as a percent) | 99.00% |