Accrued Expenses (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Mar. 31, 2012
Schedule of Accrued Liabilities [Line Items]
Employee compensation	$ 7,104	$ 9,272
Sales and income taxes	1,413	948
Research and development	965	519
Warranty	898	726
Professional, accounting and auditing fees	576	427
Other	640	588
Accrued expenses	$ 11,596	$ 12,480