Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																9 Months Ended	12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
A reconciliation between basic and diluted earnings per share computations
Net income (loss) available to common stockholders	$ (25,451)	[1]	$ (38,639)	[1]	$ (54,520)	[1]	$ (18,608)	[1]	$ 2,830	[2]	$ 3,727	[2]	$ (3,045)	[2]	$ 1,897	[2]	$ 5,409	$ (137,218)	$ 5,409	$ 41,987
Net loss available to common stockholders (in shares)																		62,459	61,937	61,415
Atributable to participating securities																	(154)			(1,029)
Net income or loss available to common stockholders, Loss (excluding income attributable to participating securities)																	5,255			40,958
Stock options, Effect of dilutive securities
Net loss available to common stockholders, Per Share Amount	$ (0.41)		$ (0.62)		$ (0.87)		$ (0.30)		$ 0.04		$ 0.06		$ (0.05)		$ 0.03			$ (2.20)	$ 0.08	$ 0.67
Stock options, effect of dilutive securities, (in shares)																			388	374
Dilutive Securities, Effect on Basic Earnings Per Share, Restricted Stock																			(153)	(1,023)
Restricted stock, effect of dilutive securities (in shares)																		0	0	0
DILUTED EPS, Loss																		$ (137,218)	$ 5,256	$ 40,964
DILUTED EPS, Shares																		62,459	62,325	61,789
DILUTED EPS, Per Share Amount	$ (0.41)		$ (0.62)		$ (0.87)		$ (0.30)		$ 0.04		$ 0.06		$ (0.05)		$ 0.03			$ (2.20)	$ 0.08	$ 0.66

[1] Loss from operations and net loss available to common stockholders reported during the three months ended March 31, June 30, September 30 and December 31, 2012 included ceiling test write-downs of $20.1 million, $53.5 million, $35.4 million and $28.1 million, respectively.

[2] Income (loss) from operations and net income (loss) available to common stockholders reported during the three months ended March 31 and June 30, 2011 included ceiling test write-downs of $5.9 million and $13.0 million, respectively.