Summary of Significant Accounting Policies, Foreign Currency Translation (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Foreign Currency Translation [Abstract]
Cumulative translation adjustment related to foreign currency adjustment	$ (65.6)	$ (85.3)	$ (79.9)
Cumulative translation adjustment related to foreign currency adjustment, tax	$ 7.1	$ 7.4	$ 7.9