Debt - Components of Interest Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt
Amortization of deferred financing costs	$ 0.2	$ 0.1	$ 0.2
Total interest expense	$ 31.2	$ 31.9	$ 37.9