Earnings Per Share - Reconciliation Between Basic and Diluted EPS (Details) - 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
A reconciliation between basic and diluted earnings per share computations
Net loss available to common stockholders	$ (389)	$ (3,085)	$ (3,385)	$ (4,918)	$ (9,659)	$ (23,306)	$ (24,143)	$ (39,137)	$ (11,776)	$ (96,245)	$ (299,929)
Net loss available to common stockholders (in shares)									21,330	18,354	16,256
Net loss available to common stockholders (in usd per share)	$ (0.02)	$ (0.15)	$ (0.16)	$ (0.23)	$ (0.46)	$ (1.31)	$ (1.38)	$ (2.09)	$ (0.55)	$ (5.24)	$ (18.45)
Stock options, effect of dilutive securities									$ 0	$ 0
Stock options, effect of dilutive securities, (in shares)									0	0
Attributable to participating securities									$ 0	$ 0
Restricted stock, effect of dilutive securities (in shares)									0	0	0
DILUTED EPS, Loss									$ (11,776)	$ (96,245)	$ (299,929)
DILUTED EPS (in shares)									21,330	18,354	16,256
DILUTED EPS, per share amount (in usd per share)	$ (0.02)	$ (0.15)	$ (0.16)	$ (0.23)	$ (0.46)	$ (1.31)	$ (1.38)	$ (2.09)	$ (0.55)	$ (5.24)	$ (18.45)