Debt Obligations - Schedule of Debt (Details) - USD ($) $ in Millions		9 Months Ended
	Feb. 23, 2021	Sep. 30, 2021	Feb. 01, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Obligations under finance leases		$ 0.1		$ 0.8
Total aggregate finance lease and debt payments		676.0		576.6
Unamortized issuance discount, issuance premium, and deferred financing costs		(2.1)		(15.1)
Less: current portion of debt obligations		(71.1)		(433.6)
Debt obligations		602.8		127.9
8.50% Senior Secured Notes, due 2026
Debt Instrument [Line Items]
Interest rate			100.00%
7.50% Convertible Senior Notes, due 2026
Debt Instrument [Line Items]
Interest rate			100.00%
Infrastructure
Debt Instrument [Line Items]
Obligations under finance leases		0.1		0.2
Infrastructure | LIBOR plus 5.85% Note, due 2023 | Real Estate Term Advance
Debt Instrument [Line Items]
Outstanding debt		0.0		71.6
Infrastructure | LIBOR plus 1.50% Line of Credit | Real Estate Term Advance
Debt Instrument [Line Items]
Outstanding debt		0.0		38.7
Infrastructure | 3.25% Note due 2026 | Real Estate Term Advance
Debt Instrument [Line Items]
Outstanding debt		$ 108.1		0.0
Infrastructure | 3.25% Note due 2026 | Real Estate Term Advance | DBM Global Credit Facilities | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate		3.25%
Infrastructure | PRIME minus 1.10% Line of Credit | Real Estate Term Advance
Debt Instrument [Line Items]
Outstanding debt		$ 72.5		0.0
Infrastructure | 4.00% Note due 2024 | Real Estate Term Advance
Debt Instrument [Line Items]
Interest rate		4.00%
Outstanding debt		$ 25.0		0.0
Infrastructure | 8.00% Note due 2024 | Real Estate Term Advance
Debt Instrument [Line Items]
Interest rate		8.00%
Outstanding debt		$ 19.6		0.0
Infrastructure | Other, various maturity dates | Real Estate Term Advance
Debt Instrument [Line Items]
Outstanding debt		$ 6.3		0.0
Infrastructure | LIBOR | LIBOR plus 5.85% Note, due 2023 | DBM Global Credit Facilities
Debt Instrument [Line Items]
Basis spread on variable rate		5.85%
Infrastructure | LIBOR | LIBOR plus 1.50% Line of Credit | Real Estate Term Advance | DBM Global Credit Facilities | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
Infrastructure | Prime Rate | PRIME minus 1.10% Line of Credit | Real Estate Term Advance | DBM Global Credit Facilities | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate		1.10%
Spectrum
Debt Instrument [Line Items]
Obligations under finance leases		$ 0.0		0.6
Spectrum | Other, various maturity dates
Debt Instrument [Line Items]
Outstanding debt		$ 2.2		2.9
Spectrum | 8.50% Note due 2021
Debt Instrument [Line Items]
Interest rate		8.50%
Outstanding debt		$ 19.3		19.3
Spectrum | 10.50% Note due 2021
Debt Instrument [Line Items]
Interest rate		10.50%
Outstanding debt		$ 32.9		32.9
Non-Operating Corporate | 11.50% Senior Secured Notes, due 2021
Debt Instrument [Line Items]
Interest rate		11.50%
Outstanding debt		$ 0.0		340.4
Non-Operating Corporate | 8.50% Senior Secured Notes, due 2026
Debt Instrument [Line Items]
Interest rate		8.50%	8.50%
Outstanding debt		$ 330.0		0.0
Non-Operating Corporate | 7.50% Convertible Senior Notes, due 2022
Debt Instrument [Line Items]
Interest rate		7.50%	7.50%
Outstanding debt		$ 3.2		55.0
Non-Operating Corporate | 7.50% Convertible Senior Notes, due 2026
Debt Instrument [Line Items]
Interest rate		7.50%
Outstanding debt		$ 51.8		0.0
Non-Operating Corporate | LIBOR plus 5.75% Line of Credit
Debt Instrument [Line Items]
Basis spread on variable rate	6.75%	5.75%
Outstanding debt		$ 5.0		$ 15.0