Components of Net Periodic Cost (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Service Cost - Benefits Earned During the Period		$ 710	$ 1,001	$ 1,039
Interest Cost of Projected Benefit Obligation		1,466	1,584	1,525
Expected Return on Plan Assets		(2,137)	(1,606)	(1,751)
Recognized Net Actuarial Loss		566	1,712	1,773
Amortization of Prior-Service Cost		269	359	300
Settlement	$ 600	649
Net Periodic Pension Cost		$ 1,523	$ 3,050	$ 2,886