v3.22.0.1
Pension and Other Postretirement Benefits - Assumptions (Details)
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Benefit obligations​      
Rate of compensation increase 2.66% 2.55%  
Net periodic benefit cost​      
Rate of compensation increase 2.54% 3.20% 3.42%
Pension benefits​      
Benefit obligations​      
Discount rate 2.76% 2.45%  
Net periodic benefit cost​      
Discount rate 2.27% 2.86% 3.12%
Weighted-average expected long-term rate of return 4.91% 6.09% 6.73%
Other postretirement benefits      
Benefit obligations​      
Discount rate 2.90% 2.61%  
Net periodic benefit cost​      
Discount rate 2.19% 2.49%