Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Change in tax rate income tax expense (benefit)	$ 56.9
Transition tax for accumulated foreign earnings, income tax expense (benefit)	0.8
Non-deductible officer's compensation provisional income tax expense	5.6
Tax depreciation provisional income tax benefit	19.7
Unrecognized tax benefits	$ 2.9	$ 2.8	$ 2.3	$ 1.8
Interest		0.1
Unrecognized tax benefits that would impact effective tax rate		2.7
Anticipated decrease in unrecognized tax positions		0.5
Federal
Income Taxes [Line Items]
Operating loss carryforwards		4.6
State
Income Taxes [Line Items]
Operating loss carryforwards		1.2
Operating loss carryforwards, valuation allowance		$ 0.2