Employee Share-Based Compensation Plans (Details 4) (Employee Stock Purchase Plan [Member])	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Employee Stock Purchase Plan [Member]
Summary weighted-average fair value of the shares issued under the ESPP Plans
Expected volatility	52.50%	53.40%	32.70%
Expected dividend yield
Expected life (in years)	3 months	3 months	3 months
Risk-free interest rate	0.10%	0.10%	0.10%