Summary of Significant Accounting Policies - Reconciliation of Shares Used to Determine Net Income per Share (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share Disclosure [Line Items]
Net income (loss)	$ (1,926)	$ 4,789	$ 4,830	$ 2,944	$ (1,023)	$ 1,082	$ 2,811	$ 1,893	$ 10,637	$ 4,763	$ (720)
Weighted average number of shares - basic	36,527,250	33,873,479	33,128,518	32,888,659	32,715,802	32,639,429	32,542,672	32,333,443	34,104,476	32,546,840	29,122,746
Weighted average number of shares outstanding - diluted	36,527,250	35,297,585	34,270,337	33,944,876	32,715,802	33,856,045	34,383,092	34,280,385	35,416,910	33,936,099	29,122,746
Warrants
Earnings Per Share Disclosure [Line Items]
Shares underlying									0	300,846	0
Options
Earnings Per Share Disclosure [Line Items]
Shares underlying									1,312,434	1,088,413	0