Income Taxes (Deferred Tax Assets (Liabilities) Classification) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Other assets	$ 161.2	$ 212.6
Total deferred tax assets	161.2	212.6
Deferred tax liabilities:
Deferred tax liabilities	(8.1)	(19.6)
Net deferred tax assets	$ 153.1	$ 193.0