Share-Based Compensation (Details 5)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate	0.90%	2.00%	2.80%
Expected volatility	64.00%	64.10%	64.20%
Dividend yield	0.60%	0.60%	0.60%
Performance unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate	0.40%	1.00%	1.70%
Expected volatility	52.80%	63.90%	64.10%
Dividend yield	0.60%	0.60%	0.60%