Fair-Value Measurements (Placement Of Assets And Liabilities Within The Fair Value Hierarchy Levels) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities Fair Value		$ 3,357
Commodity Derivatives [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Fair Value	689	758
Liabilities Fair Value	(3,247)
Commodity Derivatives [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Fair Value	0	0
Liabilities Fair Value	0	0
Commodity Derivatives [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Fair Value	0	0
Liabilities Fair Value	$ 0	$ 0