Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Statutory rate	21.00%	35.00%	35.00%
Effect of tax cuts and jobs act - Deferred federal	$ 5.9	$ 476.2	$ 0.0
Income before income taxes for U.S. operations	139.8	186.2	307.8
Income before income taxes for foreign operations	11.8	9.2	2.2
Net operating loss carryforwards	195.5
Remaining state loss carryforwards	5.7
Deferred Tax Assets, Other Loss Carryforwards	18.9
Additions for tax positions related to the current year	0.0	0.0	0.0
Additions for tax positions of prior years	3.0	4.5	1.0
Reduction in tax positions of prior years	0.3	0.0	25.8
Unrecognized tax benefits including interest and penalties that would affect the Company's effective tax rate if recognized	9.4	8.2
Total accrued interest and penalties related to uncertain tax positions	3.7	3.2
Increase (decrease) in income tax expense related to interest and penalties on unrecognized tax benefits	0.5	$ 3.3	$ 2.8
Settlement with taxing authority and lapse in statute of limitations
Income Tax Contingency [Line Items]
Reasonably possible decrease in unrecognized federal and state tax benefits within twelve months	$ 5.8