Income Taxes - Schedule of Accumulated Deferred Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Alternative minimum tax credit carryforward	$ 518
Total current	8,139us-gaap_DeferredTaxAssetsNetCurrent	4,608us-gaap_DeferredTaxAssetsNetCurrent
Total noncurrent	3,821us-gaap_DeferredTaxAssetsNetNoncurrent	4,197us-gaap_DeferredTaxAssetsNetNoncurrent
Total net assets	11,960us-gaap_DeferredTaxAssetsNet	8,805us-gaap_DeferredTaxAssetsNet
Current Assets
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Bad debts	178	127
Employee benefit accruals	102	251
Environmental reserves	864	(125)
Inventory	1,353	1,158
State taxes	1,699	1,812
Alternative minimum tax credit carryforward	518	130
Research & Development credit	2,717
Warranty	122
Valuation allowance	(453)
Other	1,039	1,255
Noncurrent Assets
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Bad debts	1,062	1,062
Employee benefit accruals	228	396
Environmental reserves	2,648	3,352
Inventory	(356)
Research & Development credit	1,669
Property	(340)	(348)
Valuation allowance	$ (1,090)	$ (265)

Deferred tax assets bad debt allowance.

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Deferred tax assets employee benefit accruals.

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Deferred Tax Assets Environmental Reserves

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Deferred tax assets warranty.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from in-process research and development costs expensed in connection with a business combination.

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-Publisher FASB

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from inventory.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards expected to be realized or consumed within one year or operating cycle, if longer.

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Amount after allocation of valuation allowances of noncurrent deferred tax asset attributable to deductible temporary differences and carryforwards. Noncurrent assets are expected to be realized or consumed after one year (or the normal operating cycle, if longer).

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from property, plant, and equipment.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from state taxes.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards.

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Amount of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards expected to be realized or consumed within one year or operating cycle, if longer.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized expected to be realized or consumed after one year (or the normal operating cycle, if longer).

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