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Employee Benefit Plans - Additional Information (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]      
Defined contribution pension plans $ 3,000 $ 3,200 $ 3,100
Equity Securities | United States      
Defined Benefit Plan Disclosure [Line Items]      
Long-term return on plan assets 9.00%    
Plan asset target allocation 38.00%    
Fixed Income | United States      
Defined Benefit Plan Disclosure [Line Items]      
Long-term return on plan assets 3.00%    
Plan asset target allocation 54.00%    
Funds | United States      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan assets 34.00%    
Multi-asset Strategies and CMRT | United States      
Defined Benefit Plan Disclosure [Line Items]      
Long-term return on plan assets 2.00%    
UK Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Accumulated benefit obligations (ABO) $ 9,100    
Plan assets 13,000    
Pension plan assets 3,900    
Defined Benefit Pension Plans      
Defined Benefit Plan Disclosure [Line Items]      
Accumulated benefit obligations (ABO) 52,873 50,350  
Expected contributions to Defined Benefit Plans in Next Fiscal Year 1,200    
Net underfunded status of defined benefit pension plans $ 2,613 $ 4,037  
Weighted-average rate determining the actuarial present value of benefit obligation 2.10% 2.90%  
Long-term return on plan assets 4.20% 4.70% 7.20%
Defined Benefit Pension Plans | CMRT      
Defined Benefit Plan Disclosure [Line Items]      
Long-term return on plan assets     7.50%