Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation (Fair Value Inputs) (Details)

v3.20.4
Share-Based Compensation (Fair Value Inputs) (Details)
12 Months Ended
Jun. 29, 2020
Jan. 31, 2020
Jan. 31, 2019
May 10, 2018
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
RSU equity awards                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Expected term (in years) 2 years 6 months 2 years 10 months 24 days 2 years 10 months 24 days 2 years 7 months 6 days        
Expected volatility 113.20% 54.80% 47.90% 51.60%        
Risk-free interest rate 0.20% 1.30% 2.40% 2.60%        
Dividend yield 0.00% 0.00% 0.00% 0.00%        
Cash-settled SARs                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Expected term (in years)         5 years 4 months 24 days 4 years 6 months 1 year 10 months 24 days 1 year 1 month 6 days
Expected volatility         60.70% 56.90% 58.60% 68.10%
Risk-free interest rate         1.70% 1.70% 1.60% 1.50%
Dividend yield         0.00% 0.00% 0.00% 0.00%