Earnings Per Common Share - Reconciliation of Weighted-Average Common Shares Outstanding Used in Calculation of Basic EPS to Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Numerator:
Net income	$ 7,832	$ 727	$ 20,965	$ 5,031	$ 10,034
Less: Net income allocated to participating securities	(58)	(80)	(205)	(209)
Numerator for basic and diluted earnings available to common stockholders	$ 7,774	$ 647	$ 20,760	$ 4,822
Denominator:
Weighted-average basic common shares outstanding (in shares)	57,595	39,125	54,403	33,916
Weighted-average diluted common shares outstanding (in shares)	57,595	39,125	54,403	33,916
Earnings (loss) per common share, basic (in usd per share)	$ 0.13	$ 0.02	$ 0.38	$ 0.14
Earnings (loss) per common share, diluted (in usd per share)	$ 0.13	$ 0.02	$ 0.38	$ 0.14