Investment in and Advances to Unconsolidated Affiliates - Affiliate Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Investments in and Advances to Affiliates [Line Items]
Current assets	$ 528.1	$ 235.1
Property and equipment, net	1,053.4	1,082.1
Other assets, net	20.8	21.2
Total assets	2,973.5	2,686.4
Current liabilities	352.5	424.2
Other liabilities	51.0	45.8
Members' deficit	339.7	349.8
Total liabilities and shareholders' equity	2,973.5	2,686.4
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Investments in and Advances to Affiliates [Line Items]
Current assets	92.6	132.8
Property and equipment, net	283.9	267.5
Other assets, net	266.4	244.9
Total assets	642.9	645.2
Current liabilities	95.4	133.5
Long-term debt	761.5	753.5
Other liabilities	29.5	42.3
Members' deficit	(243.5)	(284.1)
Total liabilities and shareholders' equity	$ 642.9	$ 645.2