Commitments and Contingencies - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
	Jan. 25, 2019	Jan. 31, 2019	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Commitment And Contingencies [Line Items]
Accrued liability			$ 4,950,000	$ 4,950,000	$ 7,538,000
Settlement Agreement | Patent Litigation
Commitment And Contingencies [Line Items]
Settlement agreement date	January 25, 2019
Number of days litigation settlement to be paid in cash	5 days
Litigation settlement in cash	$ 500,000
Number of days litigation settlement shares to be issued	30 days
Litigation settlement share issued	500,000
Number of days litigation settlement to be paid in value of stock consideration	30 days
Settlement agreement, terms				The Company has agreed (i) to pay to CAO, within five days of the Effective Date, $500,000 in cash, (ii) to issue to CAO, within 30 days of the Effective Date, 500,000 restricted shares of common stock of the Company (the “Stock Consideration”), and (iii) to pay to CAO, within 30 days of December 31, 2021, an amount in cash equal to the difference (if positive) between $1,000,000 and the value of the Stock Consideration on December 31, 2021.
Litigation settlement amount in cash equal to difference between value of stock consideration	$ 1,000,000
Contingent gain (loss) on patent litigation settlement			0	$ 0	$ (1,500,000)
Payment for litigation settlement in cash		$ 500,000
Accrued liability			$ 1,000,000	$ 1,000,000