Fair Value Measurements - Long-term Debt (Details) - USD ($)
$ in Millions |
Mar. 31, 2021 |
Dec. 31, 2020 |
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
$ 3,469.9
|
$ 3,580.5
|
| 8.00% senior secured notes due in 2025 | 8.00% Senior Secured Notes Due 2025 |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
850.0
|
850.0
|
| Fixed-rate term loans |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
1,272.9
|
1,301.9
|
| Unsecured term loans | Payroll Support Program, CARES Act |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
98.7
|
73.3
|
| 2015-1 EETC Class A |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
322.6
|
322.6
|
| 2015-1 EETC Class B |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
64.0
|
64.0
|
| 2015-1 EETC Class C |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
86.6
|
86.6
|
| 2017-1 EETC Class AA |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
207.3
|
214.4
|
| 2017-1 EETC Class A |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
69.1
|
71.5
|
| 2017-1 EETC Class B |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
58.2
|
60.6
|
| 2017-1 EETC Class C |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
85.5
|
85.5
|
| Convertible debt |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
175.0
|
175.0
|
| Revolving credit facilities |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
180.0
|
|
| Estimated Fair Value |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
3,888.8
|
3,859.9
|
| Estimated Fair Value | Revolving credit facilities |
|
|
| Debt Instrument [Line Items] |
|
|
| Carrying Value |
|
275.1
|
| Estimated Fair Value | Level 3 | 8.00% senior secured notes due in 2025 | 8.00% Senior Secured Notes Due 2025 |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
881.8
|
886.0
|
| Estimated Fair Value | Level 3 | Fixed-rate term loans |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
1,303.2
|
1,362.9
|
| Estimated Fair Value | Level 3 | Unsecured term loans | Payroll Support Program, CARES Act |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
105.5
|
83.1
|
| Estimated Fair Value | Level 3 | Revolving credit facilities |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
180.0
|
275.1
|
| Estimated Fair Value | Level 2 | 2015-1 EETC Class A |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
323.4
|
323.4
|
| Estimated Fair Value | Level 2 | 2015-1 EETC Class B |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
63.8
|
62.5
|
| Estimated Fair Value | Level 2 | 2015-1 EETC Class C |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
81.7
|
77.8
|
| Estimated Fair Value | Level 2 | 2017-1 EETC Class AA |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
207.9
|
207.4
|
| Estimated Fair Value | Level 2 | 2017-1 EETC Class A |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
67.2
|
68.8
|
| Estimated Fair Value | Level 2 | 2017-1 EETC Class B |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
56.2
|
56.2
|
| Estimated Fair Value | Level 2 | 2017-1 EETC Class C |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
79.9
|
76.3
|
| Estimated Fair Value | Level 2 | Convertible debt |
|
|
| Debt Instrument [Line Items] |
|
|
| Estimated Fair Value |
$ 538.2
|
$ 380.3
|