XML 72 R59.htm IDEA: XBRL DOCUMENT v3.21.1
Equity Incentive Plan - Assumptions used to estimate fair value of performance unit awards (Details) - $ / shares
3 Months Ended
Mar. 31, 2021
Mar. 05, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Closing stock price (USD per share)   $ 34.24
Performance unit awards | March 9, 2021    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Remaining performance period 2 years 9 months 21 days  
Risk-free interest rate (as a percent) 0.32%  
Dividend yield (as a percent) 0.00%  
Expected volatility (as a percent) 114.60%  
Closing stock price (USD per share) $ 34.66