Derivative Financial Instruments (Derivative Gains Included In Accumulated Other Comprehensive Loss (AOCL) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Derivative Financial Instruments [Abstract]
Beginning balance	$ 3,120	$ 3,284	$ 3,161	$ 3,325
Net gain on interest rate cash flow hedges	1,008		1,008
Net gain on commodity cash flow hedges	1,667	4,613	1,667	4,613
Reclassification of net gain on interest rate cash flow hedges to interest expense	(41)	(41)	(82)	(82)
Ending balance	$ 5,754	$ 7,856	$ 5,754	$ 7,856