Stock-Based Compensation Arrangements - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Share-based Awards Other than Options	$ 217,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures, Total	200,000	81,000
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, Employee Stock Purchase Plans	79,496	52,158
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	2,500
2004 Employee, Director and Consultant Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures, Total	200,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	2,435,500
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock purchase price	85.00%
Stock Issued During Period, Shares, Employee Stock Purchase Plans	79,496	52,158
Weighted-average purchase price	$ 0.29	$ 0.17
Weighted-average fair value	$ 0.34	$ 0.20
Compensation expense	3,941	1,332
Plan 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	8,860,000
New 2013 Employee Director And Consultant Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value	$ 9,392,500