Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes
Foreign operating loss carryforwards	$ 41.2
Valuation allowance	28.6
Net operating losses subject to expiration	18.3
Other Income (Expense)
Income Taxes
Income tax expense (benefit)	$ (15.0)	$ 32.6	$ 20.9