Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Taxes [Line Items]
Provision for (benefit from) income taxes	$ 316,000	$ 704,000	$ (28,000)	$ 1,136,000
Effective income tax rate	1.90%	20.50%	0.10%	5.60%
Discrete tax benefit (expenses)	$ 0