Income Taxes (Deferred Tax Assets and Deferred Tax Liabilities) (Details) - USD ($)
$ in Millions
Dec. 31, 2019
Dec. 31, 2018
Deferred tax assets:    
Net operating loss and other carryforwards $ 4,367.5 $ 4,289.8
Property and equipment, net 1,969.0 1,923.4
Debt 231.5 317.3
Investments 136.4 156.2
Derivative instruments 113.3 72.5
Share-based compensation 76.5 79.5
Leases 58.5 5.6
Other future deductible amounts 132.3 176.1
Deferred tax assets 7,085.0 7,020.4
Valuation allowance (4,235.5) (4,094.7)
Deferred tax assets, net of valuation allowance 2,849.5 2,925.7
Deferred tax liabilities:    
Property and equipment, net (169.9) (167.4)
Deferred revenue (168.1) (178.9)
Intangible assets (114.1) (193.8)
Debt (65.7) (91.0)
Right of use assets (56.8) 0.0
Other future taxable amounts (63.9) (39.3)
Deferred tax liabilities (638.5) (670.4)
Net deferred tax asset $ 2,211.0 $ 2,255.3