The Business, Basis of Presentation and Summary of Significant Accounting Policies - Balance Sheet, Topic 606 Adoption (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue (contract liabilities), non-current			$ 77
Accumulated deficit	$ (411,315)	$ (392,723)	(344,014)
Calculated under Revenue Guidance in Effect before Topic 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue (contract liabilities), non-current				$ 1,921
Accumulated deficit				$ (345,858)
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue (contract liabilities), non-current			(1,844)
Accumulated deficit			$ 1,844