New Accounting Standards Credit losses (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Stockholders' Equity Attributable to Parent	$ 4,189.1		$ 7,659.3
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders' Equity Attributable to Parent	$ 4,189.1		$ 7,659.3
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Accounting Policies [Abstract]
Stockholders' Equity Attributable to Parent		$ (7.8)
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders' Equity Attributable to Parent		(7.8)
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13 | Deferred Tax Asset
Accounting Policies [Abstract]
Stockholders' Equity Attributable to Parent		2.1
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders' Equity Attributable to Parent		2.1
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13 | Retained Earnings
Accounting Policies [Abstract]
Stockholders' Equity Attributable to Parent		(7.8)
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders' Equity Attributable to Parent		$ (7.8)