Employee Benefit Plans (Details 1) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 24, 2012
Jun. 26, 2011
Jun. 24, 2012
Jun. 26, 2011
Dec. 25, 2011
Dec. 26, 2010
Dec. 20, 2009
Net Periodic Benefit Cost              
Net periodic benefit cost $ 100 $ 100          
Defined benefit plan [Member]
              
Net Periodic Benefit Cost              
Service cost         415 396  
Interest cost         712 675  
Expected return on plan assets         (624) (526)  
Amortization of prior service cost         255 255  
Amortization of transition obligation         102 102  
Amortization of (gain) loss           (23)  
Net periodic benefit cost 200 200 400 400 860 879 800
Other Postretirement Benefit Plans, Defined Benefit [Member]
              
Net Periodic Benefit Cost              
Service cost         383 312  
Interest cost         643 557  
Amortization of prior service cost         103 103  
Amortization of (gain) loss         (28) (26)  
Net periodic benefit cost         $ 1,101 $ 947