Stockholders' Equity - Diluted Earnings per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Net (loss) income attributable to common stockholders									$ (1,705)	$ 6,785	$ 7,060
Weighted average number of common shares outstanding (in shares)									29,942	29,530	29,209
Dilutive effect of restricted stock grants after application of the treasury stock method (in shares)									0	348	190
Dilutive shares outstanding (in shares)									29,942	29,878	29,399
Basic and dilutive (loss) earnings per share attributable to common stockholders (in dollars per share)	$ (0.24)	$ 0.16	$ 0.00	$ 0.02	$ 0.01	$ 0.04	$ 0.09	$ 0.09	$ (0.06)	$ 0.23	$ 0.24