Employee Benefits - Additional information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plan Disclosure [Line Items]
Description of Defined Contribution Plan	The Company has a 401(k) Plan which covers its eligible employees. The 401(k) Plan permits the participants to defer a portion of their compensation in accordance with the provisions of Section 401(k) of the IRC. Participant contributions are limited to a maximum annual amount as set periodically by the IRC.
Employer matching contribution	50.00%
Matching contribution to 401(k) plan	$ 500,000	$ 0	$ 0
Maximum
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution percent of eligible compensation	6.00%