Quarterly report pursuant to Section 13 or 15(d)

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

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Employee Benefit Plans - Components of Postretirement Benefit Cost and Pension Cost (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2020
Dec. 31, 2019
Pension Plans, Defined Benefit [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 115 $ 124 $ 346 $ 372
Interest cost 303 322 909 968
Expected return on assets (628) (663) (1,885) (1,992)
Amortization of actuarial loss 259 242 779 726
Net pension cost and postretirement benefit cost 49 25 149 74
Other Postretirement Benefit Plans [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Interest cost 4 5 13 16
Amortization of actuarial loss 7 7 20 21
Net pension cost and postretirement benefit cost $ 11 $ 12 $ 33 $ 37