Income Taxes - Narrative (Details) $ in Millions	Dec. 31, 2017 USD ($)
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 103.0
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	26.0
Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 9.0

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319

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