Fair-Value Measurements (Placement Of Assets And Liabilities Within The Fair Value Hierarchy Levels) (Details) (Commodity Derivatives [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Fair Value	$ 306	$ 507
Liabilities Fair Value	(2,820)	(2,474)
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Fair Value
Liabilities Fair Value
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Fair Value
Liabilities Fair Value