Summary of Significant Accounting Policies Income Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 340.9	$ 10.2
Valuation Allowance, Deferred Tax Asset, Change in Amount	$ 110.1	$ (3.2)	$ (2.2)