Goodwill and Intangible Assets - Intangible Assets (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 12, 2013
Finite-Lived Intangible Assets [Line Items]
Acquisition purchase price	$ 2,454
Alter Power Systems [Member]
Finite-Lived Intangible Assets [Line Items]
Acquisition purchase price	2,454	2,454
Intangible asset in connection with acquisition	3,093
Completed technology [Member] \| Alter Power Systems [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset in connection with acquisition	2,495
Trade names [Member] \| Alter Power Systems [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset in connection with acquisition	$ 598

The amount of acquisition cost of a business combination allocated to an identifiable intangible asset that will be amortized.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 52

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_BusinessAcquisitionPurchasePriceAllocationAmortizableIntangibleAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant