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Pension Plans - Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost (Detail)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost [Abstract]      
Discount rate 3.50% 3.50% 4.25%
Rate of compensation increase 0.00% 0.00% 0.00%
Expected long-term return on plan assets 7.00% 7.00% 8.00%