Pension And Other Postretirement Benefit Plans (Components Of Net Periodic Cost) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,495	$ 2,925	$ 6,990	$ 5,901
Interest cost	9,334	9,984	18,668	19,111
Expected return on plan assets	(12,830)	(13,365)	(25,660)	(25,172)
Amortization of prior service cost	100	107	200	209
Amortization of net loss (gain)	4,816	1,391	9,623	3,369
Net periodic cost	4,915	1,042	9,821	3,418
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	29	(58)	58	57
Interest cost	127	(318)	254	285
Amortization of prior service cost	(59)	52	(118)	(50)
Amortization of net loss (gain)	(21)	125	(42)	(118)
Net periodic cost	$ 76	$ (199)	$ 152	$ 174