Schedule of Carrying Value of Trust Assets, Including Unrealized Gains or Losses (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Mar. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Investments held in Rabbi Trust	$ 8,896	$ 8,811
Unrealized losses in fair value of trust assets	72	(208)
Unrealized losses in fair value of trust assets are net of income tax expense of		(168)
Obligations under the supplemental plan	$ 25,739	$ 25,072