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		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Numerator:
Net income (loss)	$ 2,266	$ (10,342)	$ 4,304	$ (10,740)	$ (8,143)
Less: Net income allocated to participating securities	(81)	0	(117)	0
Numerator for basic and diluted earnings (loss) available to common stockholders	$ 2,185	$ (10,342)	$ 4,187	$ (10,740)
Denominator:
Weighted-average basic and diluted common shares outstanding	31,278	22,231	31,268	22,230
Basic and diluted earnings (loss) per common share	$ 0.07	$ (0.47)	$ 0.13	$ (0.48)