XML 70 R59.htm IDEA: XBRL DOCUMENT v2.4.0.6
Change in Benefit Obligations and Change in Fair Value of Plan Assets Related to Pension and Postretirement Benefit Plans (Detail) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets at plan year end $ 238,359 $ 185,122  
Pension Plans
      
Defined Benefit Plan Disclosure [Line Items]      
Benefit obligation at beginning of period 314,155 246,985 203,292
Service cost 22,424 19,808 18,315
Interest cost 14,800 13,473 12,091
Plan amendments 2,271 1,827 837
Actuarial loss 29,338 35,399 15,153
Benefits paid (4,274) (3,337) (2,703)
Benefit obligation at plan year end 378,714 314,155 246,985
Accumulated benefit obligation portion of above 341,729 280,820 214,676
Plan assets at fair value at beginning of period 185,122 167,033 140,065
Actual return on plan assets 21,527 (732) 14,457
Company contributions 35,984 22,158 15,214
Benefits paid (4,274) (3,337) (2,703)
Fair value of plan assets at plan year end 238,359 185,122 167,033
Postretirement Plans
      
Defined Benefit Plan Disclosure [Line Items]      
Benefit obligation at beginning of period 25,937 23,215 20,080
Service cost 1,856 1,599 1,399
Interest cost 1,241 1,189 1,130
Plan amendments 2,266    
Actuarial loss 1,698 755 1,931
Participant contributions 1,055 942 838
Benefits paid (2,247) (1,763) (2,163)
Benefit obligation at plan year end 31,806 25,937 23,215
Company contributions 1,192 821 1,325
Participant contributions 1,055 942 838
Benefits paid $ (2,247) $ (1,763) $ (2,163)