Basis of Presentation and Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Subsidiary, Sale of Stock [Line Items]
Stockholders' equity	$ 8,722.8	$ 9,346.4	$ 9,189.5	$ 8,829.9	$ 8,641.8	$ 1,869.9
Cumulative Effect, Period of Adoption, Adjustment
Subsidiary, Sale of Stock [Line Items]
Stockholders' equity						(1.0)
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13 | Accounts Receivable
Subsidiary, Sale of Stock [Line Items]
Stockholders' equity						(1.0)
Retained Earnings (Accumulated Deficit)
Subsidiary, Sale of Stock [Line Items]
Stockholders' equity	$ 93.8	$ (32.2)	$ (175.7)	$ (327.3)	$ (356.8)	(141.4)
Retained Earnings (Accumulated Deficit) | Cumulative Effect, Period of Adoption, Adjustment
Subsidiary, Sale of Stock [Line Items]
Stockholders' equity						(1.0)
Retained Earnings (Accumulated Deficit) | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Subsidiary, Sale of Stock [Line Items]
Stockholders' equity						$ (1.0)