Goodwill and Intangible Assets - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 169,522		$ 170,384
Intangible assets, net	52,452		54,685
Amortization expenses included in cost of product	586	482
Weighted average useful life in years of acquired intangible assets	10 years 9 months 18 days
Acquired Software And Core Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expenses included in cost of product	1,500	1,100
Weighted average useful life in years of acquired intangible assets	6 years 3 months 18 days
Other Acquired Intangible Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expenses included in cost of product	$ 635	$ 482
Customer Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life in years of acquired intangible assets	15 years 2 months 12 days