Income Taxes (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Taxes
Effective tax rate (as a percent)	35.80%	3.60%		37.20%	2.80%
Income tax provision (benefit)	$ 13,276,000	$ 1,591,000		$ 32,071,000	$ (8,905,000)
Impairment charge			376,600,000		376,574,000
Adjustment related to a favorable federal and state audit settlement	(1,800,000)			(2,100,000)
Refund received as a result of completion of audit by Internal Revenue Services	1,100,000
True-up adjustments				(1,200,000)
Adjustment related to discrete items		0
Adjustment mainly related to stock based compensation items					3,600,000
Total amount of unrecognized tax benefits, including related interest and penalties	4,500,000			4,500,000
Unrecognized tax benefits	4,200,000			4,200,000
Amount of Interest	300,000			300,000
Decrease in unrecognized tax benefits within the next twelve months due to the settlement of audits or the expiration of statute of limitations in various jurisdictions	$ 1,100,000			$ 1,100,000