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)