Property, Plant And Equipment (Schedule Of Property, Plant And Equipment) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Property, Plant And Equipment [Abstract]
Land	$ 13,509	$ 12,897
Building and improvements	135,049	129,881
Plant and equipment	2,039,050	1,963,186
Other	147,342	133,241
Property, plant and equipment, gross	2,334,950	2,239,205
Less: Accumulated depreciation	(1,196,845)	(1,098,792)
Property, plant and equipment, net, before construction in progress	1,138,105	1,140,413
Construction in progress	93,961	29,921
Property, plant and equipment, net	$ 1,232,066	$ 1,170,334