Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Effective Tax Rate Reconciliation
Income tax expense at U.S. statutory rate	$ 15.6	$ 17.9	$ 7.3
State income taxes, net of federal tax benefit	3.6	(0.9)	(2.3)
Foreign income, net of credit on foreign taxes	2.1	0.0	(1.3)
Effective tax rate differential of earnings outside of U.S.	1.8	2.4	0.0
Change in valuation allowance	(5.9)	(4.2)	1.0
Research & experimentation credits	(0.9)	(1.0)	(0.9)
Foreign derived intangible income	(0.8)	(0.2)	(1.2)
Net non-deductible items	1.6	1.2	2.3
Change in uncertain tax positions	(0.2)	(0.6)	0.0
Share-based compensation	(2.2)	(1.7)	(2.8)
Tax effect of 2017 tax reform federal rate change	0.0	(0.2)	0.0
Other items	(1.2)	2.2	0.7
Income tax expense, net	$ 13.5	$ 14.9	$ 2.8