Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Contingency [Line Items]
Effective income tax rates	(6.50%)	(17.10%)	(8.40%)	(12.20%)
Unrecognized tax benefits	$ 0.6		$ 0.6		$ 1.5
Unrecognized tax benefits income tax penalties and interest accrued	$ 0.2		0.2		0.4
Unrecognized tax benefits, reduction resulting from lapse of applicable statute of limitations			$ 1.1
State
Income Tax Contingency [Line Items]
Net operating loss carryforwards					630.7
Net operating loss carryforwards, Year of expiration			2024
Federal
Income Tax Contingency [Line Items]
Net operating loss carryforwards					$ 700.3
Net operating loss carryforwards, Year of expiration			2028