Earnings Per Share Reconciliation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 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	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
NUMERATOR
Net income (loss) from continuing operations	$ 28,947	$ 10,407	$ 6,049	$ (3,021)	$ 1,263	$ (3,890)	$ (9,801)	$ (17,439)	$ 42,382	$ (29,867)	$ (80,692)
Net loss from discontinued operations	(374)	238	223	(2,087)	(451)	(17,423)	(912)	(2,097)	(2,000)	(20,883)	(4,447)
Less: distributed earnings allocated to nonvested restricted stock									(42)	0	0
Less: undistributed earnings allocated to nonvested restricted stock									(313)	0	0
Numerator for basic income (loss) per share									40,027	(50,750)	(85,139)
Plus: interest on 1.6 percent convertible senior notes due 2018									1,829	0	0
Plus: undistributed earnings allocated to nonvested restricted stock									313	0	0
Less: undistributed earnings reallocated to nonvested restricted stock									(284)	0	0
Numerator for diluted income (loss) per share									$ 41,885	$ (50,750)	$ (85,139)
DENOMINATOR
Basic earnings per share-weighted-average shares	45,115,000	44,826,000	44,628,000	44,474,000	44,410,000	44,409,000	44,369,000	44,239,000	44,761,178	44,357,470	44,050,013
Effect of dilutive securities:
Share-based payments (in shares)									487,443	0	0
1.6 percent convertible senior notes due 2018 (in shares)									4,406,700	0	0
Diluted earnings per share-adjusted weighted-average shares and assumed conversions	53,053,000	52,654,000	48,571,000	44,474,000	45,075,000	44,409,000	44,369,000	44,239,000	49,655,321	44,357,470	44,050,013
Basic
Continuing operations (in dollars per share)	$ 0.64	$ 0.23	$ 0.14	$ (0.07)	$ 0.03	$ (0.09)	$ (0.22)	$ (0.39)	$ 0.93	$ (0.67)	$ (1.83)
Discontinued operations (in dollars per share)	$ (0.01)	$ 0.01	$ 0.00	$ (0.04)	$ (0.01)	$ (0.39)	$ (0.02)	$ (0.05)	$ (0.04)	$ (0.47)	$ (0.10)
Total (in dollars per share)	$ 0.63	$ 0.24	$ 0.14	$ (0.11)	$ 0.02	$ (0.48)	$ (0.24)	$ (0.44)	$ 0.89	$ (1.14)	$ (1.93)
Diluted
Continuing operations (in dollars per share)	$ 0.56	$ 0.21	$ 0.14	$ (0.07)	$ 0.03	$ (0.09)	$ (0.22)	$ (0.39)	$ 0.88	$ (0.67)	$ (1.83)
Discontinued operations (in dollars per share)	$ (0.01)	$ 0.01	$ 0.00	$ (0.04)	$ (0.01)	$ (0.39)	$ (0.02)	$ (0.05)	$ (0.04)	$ (0.47)	$ (0.10)
Total (in dollars per share)	$ 0.55	$ 0.22	$ 0.14	$ (0.11)	$ 0.02	$ (0.48)	$ (0.24)	$ (0.44)	$ 0.84	$ (1.14)	$ (1.93)
1.6 percent convertible senior notes due 2018
Convertible senior notes
Interest rate stated percentage	1.60%								1.60%