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Pension And Other Postretirement Benefit Plans (Components Of Net Periodic Cost) (Detail) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Pension Plans, Defined Benefit
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost $ 1,529 $ 3,495
Interest cost 9,410 9,334
Expected return on plan assets (13,212) (12,830)
Amortization of prior service cost (6) 100
Amortization of net loss (gain) 3,164 4,843
Defined Benefit Plan, Settlements, Benefit Obligation   (27)
Net periodic cost 885 4,915
Other Postretirement Benefit Plans, Defined Benefit
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 27 29
Interest cost 125 127
Amortization of prior service cost (59) (59)
Amortization of net loss (gain) (35) (21)
Net periodic cost $ 58 $ 76