Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2014 Customer	Mar. 31, 2013 Customer	Mar. 31, 2012 Customer
Summary Of Significant Accounting Policy [Line Items]
Number of customers accounted for more than 10% of total product revenues	0	0	0
Number of customers with an accounts receivable balance greater than 10% of total accounts receivable	0	0
Goodwill	$ 37,990	$ 35,410	$ 36,846
Product warranty period	1 year
Expected dividend yield	0.00%
Maximum
Summary Of Significant Accounting Policy [Line Items]
Maturity period of marketable security to be classified as cash equivalent	90 days
Minimum
Summary Of Significant Accounting Policy [Line Items]
Maturity period of security to be classified as marketable securities	90 days
Maturity period of security to be classified as long-term marketable securities	1 year
Stock Options and Performance Shares
Summary Of Significant Accounting Policy [Line Items]
Shares excluded from the calculation of diluted weighted average shares outstanding	94,000	438,000	410,000
Machinery and Equipment | Maximum
Summary Of Significant Accounting Policy [Line Items]
Property and Equipment, useful life	10 years
Machinery and Equipment | Minimum
Summary Of Significant Accounting Policy [Line Items]
Property and Equipment, useful life	2 years
Computer Software | Maximum
Summary Of Significant Accounting Policy [Line Items]
Property and Equipment, useful life	7 years
Computer Software | Minimum
Summary Of Significant Accounting Policy [Line Items]
Property and Equipment, useful life	3 years
Furniture and Fixtures | Maximum
Summary Of Significant Accounting Policy [Line Items]
Property and Equipment, useful life	10 years
Furniture and Fixtures | Minimum
Summary Of Significant Accounting Policy [Line Items]
Property and Equipment, useful life	4 years
Leasehold Improvements
Summary Of Significant Accounting Policy [Line Items]
Leasehold improvements, useful life	Shorter of the lease term or the estimated useful lives