v2.4.0.6
Employee Benefit Plans (Details) (USD $)
 12 Months Ended
Dec. 31, 2011
period
Dec. 31, 2010
Dec. 31, 2009
Employee Benefit [Line Items]      
Number of Look-back Period Under Employee Stock Purchase Plan 2    
Look-back Period Under Employee Stock Purchase Plan 6 months    
Discount On Common Stock Under Employee Stock Purchase Plan, Percent 10.00%    
Stock Issued During Period, Shares, Employee Stock Purchase Plans 39,989 35,806 55,443
Stock Issued During Period, Value, Employee Stock Purchase Plan $ 690,000 $ 614,000 $ 578,000
Shares Available For Purchase Under Employee Stock Purchase Plan 647,903    
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]      
Balance at beginning of year 10,363,000 9,947,000  
Change in actuarial loss 329,000 (78,000)  
Benefit expense 987,000 928,000  
Benefit payments (442,000) (434,000)  
Balance at end of year 11,237,000 10,363,000 9,947,000
Defined Contribution Pension [Member]
      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Service Period 6 months    
Deferred Compensation Arrangement with Individual, Contribution To Plan By Employee, Percent Of Eligible Compensation 75.00%    
Deferred Compensation Arrangement with Individual, Contribution Requirements, Matching Percent 50.00%    
Deferred Compensation Arrangement with Individual, Employer Contribution 1,175,000 866,000 748,000
Defined Contribution Pension [Member] | Minimum [Member]
      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Eligible Age 18    
Defined Contribution Pension [Member] | Maximum [Member]
      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Contribution Requirements, Percent Of Each Employee Compensation 3.00%    
Deferred Profit Sharing [Member]
      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Service Period 6 months    
Deferred Compensation Arrangement with Individual, Contribution To Plan By Employee, Percent Of Eligible Compensation 75.00%    
Deferred Compensation Arrangement with Individual, Contribution Requirements, Matching Percent 50.00%    
Deferred Compensation Arrangement with Individual, Employer Contribution 2,600,000 1,200,000 0
Deferred Profit Sharing [Member] | Minimum [Member]
      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Eligible Age 18    
Deferred Profit Sharing [Member] | Maximum [Member]
      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Contribution Requirements, Percent Of Each Employee Compensation 3.00%    
ESP Plan [Member]
      
Employee Benefit [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date 90.00%    
Unit Plans [Member]
      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Recorded Liability 4,400,000 4,000,000  
Deferred Compensation Arrangement with Individual, Compensation Expense 655,000 750,000 530,000
Unit Plans [Member] | Minimum [Member]
      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Vesting Period 4 years    
Deferred Compensation Arrangement with Individual, Benefit Period 5 years    
Unit Plans [Member] | Maximum [Member]
      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Vesting Period 10 years    
Deferred Compensation Arrangement with Individual, Benefit Period 10 years    
SERP [Member]
      
Employee Benefit [Line Items]      
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate 5.30% 5.90%  
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Normal Retirement Age 65    
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Annual Cost Of Living Benefit Adjustment 2.00%    
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]      
2012 510,000    
2013 526,000    
2014 555,000    
2015 572,000    
2016 803,000    
2017 through 2021 5,864,000    
Total $ 8,830,000