Income Taxes - Schedule of Accumulated Deferred Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Alternative minimum tax credit carryforward	$ 130
Total current	4,608	6,757
Total noncurrent	4,197	4,289
Total net assets	8,805	11,046
Current Assets
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Bad debts	127
Employee benefit accruals	251	279
Environmental reserves	(125)	1,571
Inventory	1,158	1,231
State taxes	1,812	1,744
Alternative minimum tax credit carryforward	130	847
Other	1,255	1,085
Noncurrent Assets
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Bad debts	1,062	1,177
Employee benefit accruals	396	494
Environmental reserves	3,352	1,753
Property	(348)	1,448
Valuation allowance	$ (265)	$ (583)