Derivatives (Fair Value Of Derivative Instruments And Locations In Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Current derivative asset	$ 4,514	$ 16,552
Non-current derivative asset	1,133	0
Total derivatives assets	5,647	16,552
Current derivative liabilities	6,480	1,948
Non-current derivative liabilities	938	562
Total derivative liabilities	7,418	2,510
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Current derivative asset	486	13,674
Non-current derivative asset	0	0
Total derivatives designated as hedging instruments, assets	486	13,674
Current derivative liabilities	1,750	1,005
Non-current derivative liabilities	0	0
Total derivatives designated as hedging instruments, liabilities	1,750	1,005
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Current derivative asset	4,028	2,878
Non-current derivative asset	1,133	0
Total derivatives designated as hedging instruments, assets	5,161	2,878
Current derivative liabilities	4,730	943
Non-current derivative liabilities	938	562
Total derivatives designated as hedging instruments, liabilities	$ 5,668	$ 1,505