Annual report pursuant to Section 13 and 15(d)

Benefit Plans (Details Textuals)

v2.4.0.6
Benefit Plans (Details Textuals) (USD $)
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets, Percentage 100.00% 100.00%  
Benefit Plans (Textuals) [Abstract]      
Contribution to plan $ 90,000,000    
Employees retirement age for health care and life insurance benefits under unfunded defined benefit post-retirement plan 55 years    
Employees vesting service under defined benefit post-retirement plan, minimum 10 years    
Life insurance coverage, maximum 50,000    
Average duration of plan assets investment in bonds, years 3.3Y    
Target allocation of plan assets in equity, percentage 70.00%    
Target allocation of plan assets in bonds, percentage 30.00%    
Base pay contributed to the plan up to first 3%    
Attributes of employees contribution to defined contribution plan Half of the employee contribution was matched on the 4th and 5th percent of base pay contributed to the Plan.    
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]      
Effect of One Percentage Point Increase on Service and Interest Cost Components 1,000,000    
Effect of One Percentage Point Decrease on Service and Interest Cost Components 200,000    
Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation 1,000,000    
Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation 200,000    
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate 2028    
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate 4.50%    
Defined Benefit Plan, Description of Direction and Pattern of Change for Assumed Health Care Cost Trend Rate These rates are assumed to decrease gradually    
Defined Benefit Plan, Accumulated Benefit Obligation 651,300,000 575,900,000  
Defined Benefit Plan, Funded Status of Plan 112,400,000    
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]      
Defined Benefit Plan, Amortization of Net Transition Asset (Obligation) 1,000,000    
Defined Benefit Plan, Amortization of Net Prior Service Cost (Credit) 6,900,000    
Defined Benefit Plan, Amortization of Net Gains (Losses) 26,800,000    
Estimated Net Periodic Pension Cost In Next Fiscal Year 38,700,000    
Estimated Net Periodic Post Retirement Benefit Cost In Next Fiscal Year 0    
Defined Benefit Plan Expenses 800,000 1,000,000 700,000
Contributions Received For Retiree Medical Program 2,900,000    
Estimated Life Of Benefit Obligations 13Y    
Pension and Other Postretirement Defined Benefit Plans, Liabilities 26,900,000 23,100,000  
Post Retirement Benefits [Member]
      
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]      
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year $ 3,500,000    
Pre 65 [Member]
      
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]      
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year 8.00%    
Post 65 [Member]
      
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]      
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year 8.50%    
Equity Securities [Member]
      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets, Percentage 61.00%    
Covered Bonds [Member]
      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets, Percentage 32.00%