Income Tax Expense - Gross Unrecognized Income Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Gross Unrecognized Income Tax Benefits [Roll Forward]
Balance at January 1	$ 1.3	$ 1.4	$ 1.4
Additions for Tax Positions Related to the Current Year	0.0	0.0	0.1
Reduction for Tax Positions Related to Prior Years	0.0	(0.1)	(0.1)
Balance as of December 31	1.3	1.3	1.4
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	0.6
Unrecognized Tax Benefits, Accrued Interest		0.0	0.0
Unrecognized Tax Benefits, Penalties	0.0	$ 0.0	$ 0.0
Material Changes to Unrecognized Tax Benefits Expected During Next 12 Months	$ 0.0