Stock-Based Compensation - Effects of Stock-Based Compensation Related to Equity Awards to Employees and Nonemployees on Condensed Statement of Operations and Comprehensive Loss (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 112,999	$ 331,977	$ 447,504	$ 883,672
Stock Options [Member] | Cost of revenues [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	10,150	59,720	37,150	133,105
Stock Options [Member] | Research and Development Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	30,247	53,405	103,267	121,834
Stock Options [Member] | General and Administrative Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	57,162	178,671	243,593	528,406
Stock Options [Member] | Sales and Marketing Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	15,440	40,181	63,494	100,327
RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 112,999	475,688	511,929	1,232,149
RSUs [Member] | Cost of revenues [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation		20,417	(18,802)	58,717
RSUs [Member] | Research and Development Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation		20,418	13,576	57,490
RSUs [Member] | General and Administrative Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation		74,521	54,303	160,927
RSUs [Member] | Sales and Marketing Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation		$ 28,355	$ 15,348	$ 71,343