v3.21.2
Segment information - Revenue net (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]      
Revenues $ 4,293 $ 5,115 $ 1,570
Hong Kong      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Revenues 4,235 5,115 1,570
Australia      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Revenues $ 58 $ 0 $ 0