Fair Value Measurements (Reconciliations Of Level 3 Fair Value Measurements) (Details) (Collar [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Collar [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Beginning of period	$ (595)		$ 33,615
Included in earnings	(2,637)	[1]	24,484	[1]
Included in other comprehensive income (loss)	0		(11,641)
Settlements	637		(25,129)
Transfers out of Level 3 into Level 2	0		(21,924)
End of period	(2,595)		(595)
Total gains for the period included in earnings attributable to the change in unrealized gain relating to assets still held at end of period	$ (2,000)		$ (645)

[1] Commodity sales collars are reported in the consolidated statements of income in oil and gas revenues (for cash flow hedges), and gain (loss) on derivatives not designated as hedges and hedge ineffectiveness, net, respectively.