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Employee Benefit Plans (Net Periodic Benefit Cost (Benefit)) (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Retirement Benefits [Abstract]      
Expected return on plan assets, net of expenses $ (12,289) $ (10,772) $ (11,916)
Interest cost on projected benefit obligation 5,010 6,472 5,898
Net amortization and deferral 5,319 5,623 5,002
Net periodic expense (benefit) $ (1,960) $ 1,323 $ (1,016)