Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S. federal corporate income tax rate (percent)	21.00%	35.00%
Tax effect for re-measurement of deferred tax balances as result of Tax Act		$ 31.9
Provisional income tax expense related to remeasurement of deferred taxes at newly enacted tax rate		30.0
Net operating loss carryforwards	$ 225.1	$ 210.3
Market capitalization used in net operating loss analysis	124.5
Limitation on loss carryforward based Section 382 change in ownership	$ 3.0