Annual report pursuant to Section 13 and 15(d)

Commitments - Narrative (Details)

v3.20.4
Commitments - Narrative (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Commitments [Line Items]      
Percentage decrease in future demand reservation fees 50.00%    
Percentage decrease in future demand reservation volume 35.00%    
Maximum annual contributions per employee (401K Plan) 100.00%    
Minimum matching employer contribution for 401K 50.00%    
Cost recognized on defined contribution plan $ 2.6 $ 2.9 $ 2.6
Minimum      
Commitments [Line Items]      
Minimum matching employer contribution for 401K 4.00%    
Maximum      
Commitments [Line Items]      
Minimum matching employer contribution for 401K 6.00%