Goodwill and Intangible Assets Net - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Disposal or recognition of additional goodwill	$ 0		$ 0
Impairment charges on goodwill	0		0
Goodwill balance	1,316,000		1,316,000		1,316,000
Amortization expenses of intangible assets	50,000	50,000	151,000	151,000
Impairment charges recognized related to the acquired intangible assets	0	0	0	0
Annual amortization expense of the intangible assets, 2013 (remaining six months)	50,000		50,000
Annual amortization expense of the intangible assets, 2014	200,000		200,000
Annual amortization expense of the intangible assets, 2015	200,000		200,000
Annual amortization expense of the intangible assets, 2016	200,000		200,000
Annual amortization expense of the intangible assets, 2017	200,000		200,000
Annual amortization expense of the intangible assets, 2018	200,000		200,000
Annual amortization expense of the intangible assets, 2019	200,000		200,000
Annual amortization expense of the intangible assets, 2020	$ 100,000		$ 100,000