Schedule II - Consolidated Valuation and Qualifying Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Allowance for Doubtful Accounts
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance At Beginning of Period	$ 323	$ 292	$ 283
Charged to Costs and Expenses	365	31	17
Deductions	120		8
Balance at End of Period	568	323	292
Inventory Reserves
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance At Beginning of Period	2,929	3,116	2,694
Charged to Costs and Expenses	238	291	540
Deductions	621	478	118
Balance at End of Period	2,546	2,929	3,116
Environmental Reserves
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance At Beginning of Period	10,323	12,684	13,535
Charged to Costs and Expenses	290	333	394
Deductions	1,358	2,694	1,245
Balance at End of Period	9,255	10,323	12,684
Allowance For Tax Loss Valuation
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance At Beginning of Period	265	583	265
Charged to Costs and Expenses	1,278		318
Deductions		318
Balance at End of Period	$ 1,543	$ 265	$ 583

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 09

-Article 12

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