Derivatives And Risk Management (Balance Sheet Classification) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Derivative assets	$ 78,503	$ 292,144
Derivative liabilities	40,490	4,266
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative assets	20,631	287,993
Derivative liabilities	3,884
Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Derivative Asset [Member]
Derivative [Line Items]
Derivative assets	20,631	279,443
Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Other Long-Term Assets [Member]
Derivative [Line Items]
Derivative assets		8,550
Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	3,884
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative assets	57,872	4,151
Derivative liabilities	36,606	4,266
Not Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Derivative Asset [Member]
Derivative [Line Items]
Derivative assets	37,382
Not Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	185
Not Designated as Hedging Instrument [Member] | Basis Swaps [Member] | Derivative Asset [Member]
Derivative [Line Items]
Derivative assets	12,858	3,250
Not Designated as Hedging Instrument [Member] | Basis Swaps [Member] | Other Long-Term Assets [Member]
Derivative [Line Items]
Derivative assets	107	901
Not Designated as Hedging Instrument [Member] | Basis Swaps [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	1,501	138
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other Long-Term Assets [Member]
Derivative [Line Items]
Derivative assets	7,525
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	1,520
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other Long-Term Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	3,012
Not Designated as Hedging Instrument [Member] | Fixed Price Call Options [Member] | Other Long-Term Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	$ 30,388	$ 4,128