Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Income Tax Contingency [Line Items]
Effective income tax rates	3.70%	(9.90%)
Unrecognized tax benefits			$ 0.6
Unrecognized tax benefits income tax penalties and interest accrued			0.2
Unrecognized tax benefits, reduction resulting from lapse of applicable statute of limitations	$ 0.5
Federal
Income Tax Contingency [Line Items]
Net operating loss carryforwards			$ 1,100.0
Net operating loss carryforwards, Year of expiration			2028
State
Income Tax Contingency [Line Items]
Net operating loss carryforwards			$ 572.2
Net operating loss carryforwards, Year of expiration			2024
Other state
Income Tax Contingency [Line Items]
Net operating loss carryforwards			$ 535.8