Stock-Based Compensation Arrangements - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
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	$ 1,300,000
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, Employee Stock Purchase Plans	67,610	50,624
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited		2,500
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock purchase price	85.00%
Weighted-average purchase price	$ 0.29	$ 0.26
Weighted-average fair value	$ 0.34	$ 0.30
Compensation expense	$ 3,450	$ 2,208
2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Payment Award, Number of Shares Authorized	8,860,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	6,148,700
2004 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Payment Award, Number of Shares Authorized	2,435,500
2013 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, Gross	137,000