Annual report pursuant to Section 13 and 15(d)

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

v3.19.1
Employee Benefit Plans - Components of Postretirement Benefit Expense (Income) and Pension Cost (Benefit) (Detail) - Other Postretirement Benefit Plans [Member] - USD ($)
$ in Thousands
 12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]      
Interest cost on accumulated benefit obligation $ 25 $ 26 $ 26
Amortization of actuarial loss 28 37 36
Net pension (benefit) cost and postretirement benefit expense $ 53 $ 63 $ 62