XML 114 R63.htm IDEA: XBRL DOCUMENT v2.4.0.6
Employee Savings Plan (Details) (USD $)
 12 Months Ended
Dec. 31, 2011
days
Dec. 31, 2010
Dec. 31, 2009
Employee Savings Plan [Abstract]      
Number of days of service required for employee to participate 30    
Employer contributions to the plan, maximum percentage 2.50%    
Discretionary profit-sharing contribution percentage of the employee's salary 1.50%    
Employer contributions to the plan $ 11,866,000 $ 11,376,000 $ 11,750,000