Organization and Basis of Presentation - Additional Information (Detail)		6 Months Ended
	May 15, 2019 d $ / shares	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Organization And Basis Of Presentation [Abstract]
Month and year of incorporation		2007-01
Cash and cash equivalents | $		$ 7,440,079	$ 5,319,004	$ 6,531,079	$ 7,679,267
Minimum common stock closing bid price | $ / shares	$ 1.00
Initial period to regain compliance	180 days
Number of minimum consecutive business days | d	10
Closing bid price description		On May 15, 2019, the Company received a letter from Nasdaq indicating that, for the last thirty consecutive business days, the bid price for the Company’s common stock had closed below the minimum $1.00 per share requirement for continued listing on The Nasdaq Capital Market. In accordance with Nasdaq listing rules, the Company has been provided an initial period of 180 calendar days, or until November 11, 2019, to regain compliance. The letter states that Nasdaq will provide written notification that the Company has achieved compliance with its rules if at any time before November 11, 2019, the bid price of the Company’s common stock closes at $1.00 per share or more for a minimum of ten consecutive business days. The Nasdaq letter has no immediate effect on the listing or trading of the Company’s common stock and the common stock will continue to trade on The Nasdaq Capital Market.