Fair Value Measurements and Derivatives (Textuals) (Details) T in Millions, $ in Millions, € in Billions |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2019
EUR (€)
T
|
Dec. 31, 2019
USD ($)
T
|
Dec. 31, 2018
USD ($)
|
|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||
| Fair value of long-term debt | $ 6,957.8 | $ 6,601.9 | |
| Fair value of long-term debt in excess of carrying value | $ 31.3 | $ 8.4 | |
| Fuel contracts | |||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||
| Derivative maturing date | Dec. 31, 2022 | ||
| Projected fuel purchases | T | 1.1 | 1.1 | |
| Foreign currency contracts | |||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||
| Notional amount of derivatives | € 1.8 | $ 2,000.0 | |
| Interest rate contracts | |||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||
| Notional amount of derivatives | $ 1,700.0 |