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Postretirement Benefit Plans - Defined Benefit Plans - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Feb. 24, 2021
Feb. 24, 2020
Feb. 21, 2019
Defined Benefit Plan Disclosure [Line Items]            
Assets gains or losses added for prior year 80.00%          
Assets gains or losses added for second preceding year 60.00%          
Assets gains or losses added for third preceding year 40.00%          
Assets gains or losses added for fourth preceding year 20.00%          
United States [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Common shares sold to the Company's ESOP trust       31,362 31,706 32,299
Expected long-term rate of return on assets 6.75% 6.75% 6.75%      
Expected payment related to qualified plan $ 0          
Expected payment related to non-qualified plan $ 290,000          
U.K Plans [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Expected long-term rate of return on assets 1.13% 2.30% 3.82%      
Percentage of premium estimated return for equities and properties to risk free rate 3.70%          
Percentage of long term return in cash 0.10%          
Expected payment related to qualified plan $ 505,000          
Equities [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Percentage of target allocation for investment category 25.00%          
Percentage of target allocation for investment including stock category 35.00%          
Expected long-term rate of return on assets 7.81%          
Equities [Member] | U.K Plans [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Percentage of target allocation for investment category 13.00%          
Debt Securities [Member] | United States [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Percentage of target allocation for investment category 63.00%          
Debt Securities [Member] | U.K Plans [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Percentage of target allocation for investment category 74.00%          
Cash [Member] | United States [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Percentage of target allocation for investment category 2.00%          
Cash [Member] | U.K Plans [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Percentage of target allocation for investment category 9.00%          
Insurance Contracts [Member] | U.K Plans [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Percentage of target allocation for investment category 4.00%          
U.S. and international equities [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Expected long-term rate of return on assets 4.13%