Earnings 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
A reconciliation between basic and diluted earnings per share computations
Net income (loss) available to common stockholders	$ (64,696)	$ (51,910)	$ (61,083)	$ (122,240)	$ 1,745	$ 4,671	$ 9,592	$ 10,043	$ (299,929)	$ 26,051	$ 8,943
Net loss available to common stockholders (in shares)									65,022	64,204	63,054
Net loss available to common stockholders (in usd per share)	$ (0.98)	$ (0.80)	$ (0.94)	$ (1.89)	$ 0.02	$ 0.07	$ 0.15	$ 0.15	$ (4.61)	$ 0.39	$ 0.14
Stock options, effect of dilutive securities									$ 0
Stock options, effect of dilutive securities, (in shares)										21	154
Attributable to participating securities									$ 0	$ (854)	$ (256)
Restricted stock, effect of dilutive securities (in shares)									0	0	0
Attributable to participating securities, basic										$ (855)	$ (257)
Net income or loss available to common stockholders, Loss (excluding income attributable to participating securities)										25,196	8,686
DILUTED EPS, Loss									$ (299,929)	$ 25,197	$ 8,687
DILUTED EPS (in shares)									65,022	64,225	63,208
DILUTED EPS, per share amount (in usd per share)	$ (0.98)	$ (0.80)	$ (0.94)	$ (1.89)	$ 0.02	$ 0.07	$ 0.15	$ 0.15	$ (4.61)	$ 0.39	$ 0.14