Net Income (Loss) Per Common Share - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jul. 31, 2013
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Amounts allocated to participating securities	$ 0	$ 0	$ 0	$ 0
Participating securities outstanding, shares	0	0	0	0
Convertible Notes [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Aggregate principal amount					$ 125,000,000
Aggregate principal amount of outstanding debt	$ 60,800,000		$ 60,800,000