Summary of Operations and Significant Accounting Policies - Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net income (loss)	$ (2,908)	$ (8,654)	$ (12,447)	$ (6,132)	$ 4,677	$ (3,699)	$ 992	$ (583)	$ (30,141)	$ 1,387	$ (15,987)
Less: Undistributed income (loss) allocated to participating securities									(275)	18	(220)
Income (loss) attributable to common stockholders									$ (29,866)	$ 1,369	$ (15,767)
Basic weighted-average number of common shares outstanding (in shares)	21,676	21,687	21,715	21,696	21,563	21,536	21,477	21,465	21,773	21,554	20,103
Add: dilutive effect of equity instruments (in shares)									0	525	0
Diluted weighted-average number of common shares outstanding (in shares)	21,676	21,687	21,715	21,696	21,947	21,536	22,035	21,465	21,773	22,079	20,103
Earnings (loss) per share - basic (in dollars per share)	$ (0.13)	$ (0.40)	$ (0.57)	$ (0.28)	$ 0.21	$ (0.17)	$ 0.05	$ (0.03)	$ (1.37)	$ 0.06	$ (0.78)
Earnings (loss) per share - diluted (in dollars per share)	$ (0.13)	$ (0.40)	$ (0.57)	$ (0.28)	$ 0.21	$ (0.17)	$ 0.05	$ (0.03)	$ (1.37)	$ 0.06	$ (0.78)