Schedule II - Valuation Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 1.6	$ 1.6	$ 1.6
Charged to Expense	0.0	0.0	0.0
Deductions	0.0	0.0	0.0
Other	0.0	0.0	0.0
Ending balance	1.6	1.6	1.6
Deferred tax asset valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	136.0	111.2	106.4
Charged to Expense	10.9	24.8	4.8
Deductions	0.0	0.0	0.0
Other	0.0	0.0	0.0
Ending balance	$ 146.9	$ 136.0	$ 111.2