Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Components of Postretirement Benefit Cost (Income) and Pension Cost (Benefit) (Detail)

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Employee Benefit Plans - Components of Postretirement Benefit Cost (Income) and Pension Cost (Benefit) (Detail) - Pension Plans, Defined Benefit [Member] - USD ($)
$ in Thousands
 12 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]      
Service cost during the period $ 461 $ 496 $ 571
Interest cost on projected benefit obligation 1,211 1,290 1,339
Expected return on assets (2,513) (2,657) (3,062)
Actuarial loss 1,039 969 847
Net pension (benefit) cost and postretirement benefit expense $ 198 $ 98 $ (305)