Income Taxes - Narrative (Details) $ in Millions	Dec. 31, 2018 USD ($)
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 104.7
Operating loss carryforwards, subject to expiration	102.5
Operating loss carryforwards, not subject to expiration	2.2
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	23.3
Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 0.8