XML 176 R122.htm IDEA: XBRL DOCUMENT v3.22.0.1
Share-based compensation - Additional Information (Details) - USD ($)
1 Months Ended 12 Months Ended
Mar. 01, 2014
Jun. 30, 2019
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based compensation            
Income tax benefit     $ 1,400,000 $ 1,000,000.0 $ 1,400,000  
Long-term incentive plan (LTIP)            
Share-based compensation            
Performance period     3 years      
Exception to forfeiture, minimum requisite service period     12 months      
Payout low end of range     0.00%      
Payout high end of range     200.00%      
Restricted stock units            
Share-based compensation            
Fair value     $ 3,000,000 4,200,000 3,200,000  
Income tax benefit     600,000 700,000 500,000  
Unrecognized compensation cost     $ 4,600,000      
Weighted-average period over which unrecognized compensation cost expected to be recognized     2 years      
LTIP linked to TRS            
Share-based compensation            
Fair value     $ 800,000 2,600,000    
Income tax benefit     200,000 400,000    
Unrecognized compensation cost     $ 1,000,000      
Weighted-average period over which unrecognized compensation cost expected to be recognized     1 year 7 months 6 days      
LTIP awards linked to other performance conditions            
Share-based compensation            
Fair value     $ 1,700,000 7,600,000 $ 0  
Income tax benefit     400,000 $ 1,200,000    
Unrecognized compensation cost     $ 3,400,000      
Weighted-average period over which unrecognized compensation cost expected to be recognized     1 year 8 months 12 days      
Equity and Incentive Plan (EIP)            
Share-based compensation            
Additional shares available for issuance (in shares) 1,500,000          
Shares remaining available for future issuance (in shares)     2,900,000      
Shares that can be issued upon vesting of outstanding units and achievement of performance goals (in shares)     500,000      
Equity and Incentive Plan (EIP) | Restricted shares            
Share-based compensation            
Vesting period     3 years 4 years 4 years 4 years
Equity and Incentive Plan (EIP) | Restricted shares | Share-based Payment Arrangement, Tranche One            
Share-based compensation            
Vesting percentage     33.33% 25.00% 25.00% 25.00%
Equity and Incentive Plan (EIP) | Restricted shares | Share-based Payment Arrangement, Tranche Two            
Share-based compensation            
Vesting percentage     33.33% 25.00% 25.00% 25.00%
Equity and Incentive Plan (EIP) | Restricted shares | Share-based Payment Arrangement, Tranche Three            
Share-based compensation            
Vesting percentage     33.33% 25.00% 25.00% 25.00%
Equity and Incentive Plan (EIP) | Restricted shares | Share-Based Payment Arrangement, Tranche Four            
Share-based compensation            
Vesting percentage       25.00% 25.00% 25.00%
Nonemployee Director Stock Plan            
Share-based compensation            
Additional shares available for issuance (in shares)   300,000        
Shares remaining available for future issuance (in shares)     244,347