Derivatives And Fair Value Measurements (Estimated Fair Value Of Derivative Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Current derivative assets	$ 48,454	$ 57,523
Noncurrent derivative assets	28,037	73,357
Current derivative liabilities	5,965	3,125
Noncurrent derivative liabilities	7,721	323
Asset Derivatives [Member]
Derivatives, Fair Value [Line Items]
Total derivative assets	121,233	165,378
Liability Derivatives [Member]
Derivatives, Fair Value [Line Items]
Total derivative liabilities	58,428	37,946
Not Designated as Hedging Instrument [Member] | Asset Derivatives [Member]
Derivatives, Fair Value [Line Items]
Current derivative assets	51,361	60,063
Noncurrent derivative assets	69,847	105,315
Current derivative liabilities	0	0
Noncurrent derivative liabilities	25	0
Not Designated as Hedging Instrument [Member] | Liability Derivatives [Member]
Derivatives, Fair Value [Line Items]
Current derivative assets	2,907	2,540
Noncurrent derivative assets	41,810	31,958
Current derivative liabilities	5,965	3,125
Noncurrent derivative liabilities	$ 7,746	$ 323