Leases - Cumulative Effect of Changes for Adoption of ASC 842 (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use operating lease assets	$ 980	$ 1,592
Other accrued liabilities	1,976	6,077	$ 6,099
Operating lease liabilities - current	300	650	0
Operating lease liabilities - non-current	680	942	0
Accumulated Deficit	$ (110,325)	(102,473)	$ (102,495)	$ (102,467)
Adjustments Upon Adoption of ASC 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use operating lease assets		1,592
Other accrued liabilities		(22)
Operating lease liabilities - current		650
Operating lease liabilities - non-current		942
Accumulated Deficit		$ 22