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
	Mar. 31, 2019	Mar. 31, 2018
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 102,459	$ 183,166
Stock Options [Member] | Cost of revenues [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	8,147	17,579
Stock Options [Member] | Research and Development Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	28,194	37,147
Stock Options [Member] | General and Administrative Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	47,581	105,175
Stock Options [Member] | Sales and Marketing Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	18,537	23,265
RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 102,459	225,263
RSUs [Member] | Cost of revenues [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation		(17,250)
RSUs [Member] | Research and Development Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation		10,015
RSUs [Member] | General and Administrative Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation		40,059
RSUs [Member] | Sales and Marketing Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation		$ 9,273