Share-based Compensation Assumptions Used for Determining the Grant Date Fair Values of Performance Shares Awarded (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Plan With the RSTR Market-Based Performance Condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date Fair Value per Share	$ 13.78	$ 23.89	$ 12.26
Expected volatility	85.00%	62.00%	61.60%
Risk-free interest rate	0.40%	1.10%	1.45%
Expected life (in years)	2 years 9 months 22 days	2 years 10 months 2 days	2 years 9 months 18 days
Expected dividend yield	0.00%	0.00%	0.00%
Stock Options | Long-Term Compensation Plan - 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility			58.50%
Risk-free interest rate			2.30%
Expected life (in years)			5 years 6 months
Expected dividend yield			1.20%
Chief Executive Officer | Plan With the RSTR Market-Based Performance Condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date Fair Value per Share	$ 16.65	$ 10.61	$ 5.57
Expected volatility	60.70%	60.70%	60.70%
Risk-free interest rate	0.34%	0.34%	0.34%
Expected life (in years)	2 years 2 months 16 days	1 year 2 months 16 days	0 years 2 months 16 days
Expected dividend yield	0.00%	0.00%	0.00%