Commitments and Contingencies - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended
Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Commitments And Contingencies Disclosure [Abstract]
Operating lease agreement rent expense		$ 856,000	$ 807,000	$ 550,000
Operating lease agreement expiration extended date	2016-08
Purchase obligations		$ 2,600,000

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717

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