XML 25 R55.htm IDEA: XBRL DOCUMENT v2.4.0.6
Significant Accounting Policies (Details 3)
 12 Months Ended
Dec. 31, 2011
Year
Plan
Dec. 31, 2010
Year
Dec. 31, 2009
Year
Significant Accounting Policies      
Number of non-qualified plans of the entity (in number of plans) 5    
Assumptions used in the Black-Scholes single option pricing model      
Range of expected lives of options (in years) 4.75 4.75 4.75
Range of expected stock price volatilities, low end range (as a percent) 53.00% 52.40% 42.00%
Range of expected stock price volatilities, high end range (as a percent) 56.60% 53.90% 52.00%
Weighted average expected stock price volatilities (as a percent) 53.20% 53.30% 46.30%
Range of risk-free interest rates, low end range (as a percent) 0.80% 1.20% 1.30%
Range of risk-free interest rates, high end range (as a percent) 2.10% 2.50% 2.10%
Expected dividend yield (as a percent) 0.00% 0.00% 0.00%