Financial Instruments - Additional Information (Detail) (USD $)		12 Months Ended
Aug. 09, 2012	Dec. 31, 2012 GovDelivery
Derivatives, Fair Value [Line Items]
Outstanding term loan	$ 10,000,000
Estimated fair value of contingent consideration liability at acquisition date		700,000
Current estimated fair value of contingent consideration liability		0
Gain on change in fair value of contingent consideration obligations		$ 700,000

This element represents the amount of any change recognized during the period in the high-end of the estimated range of outcomes (undiscounted) of a liability assumed in a business combination arising from an item of contingent consideration.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 4

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=7488404&loc=d3e7008-128479

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 72

-Subparagraph b

-Clause 2

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration