Organization and Summary of Significant Accounting Policies - Geographical Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by area	$ 0	$ 511
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by area	0	364
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by area	0	142
Other Countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by area	$ 0	$ 5