Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Energy Assets (Details)

v3.20.4
Summary of Significant Accounting Policies - Energy Assets (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Revenue, Major Customer [Line Items]    
Grant proceeds $ 1,874 $ 784
United States    
Revenue, Major Customer [Line Items]    
Deferred grant income $ 8,271 $ 6,885