Equipment and Improvements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2013
Property, Plant and Equipment [Line Items]
Leasehold improvements amortization description	Leasehold improvements are amortized using the straight-line method over the shorter of the estimated useful life of the asset or the lease term.
Net book value of equipment and improvements written off	$ 1.0
Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of the asset	7 years
Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of the asset	3 years

Amount, after cash payment, of expenses associated with exit or disposal activities pursuant to an authorized plan and expenses resulting from the write-down of assets. Excludes expenses related to a business combination, a discontinued operation or an asset retirement obligation.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Name:	us-gaap_RestructuringCostsAndAssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration