Fair Value Measurements (Reconciliations Of Level 3 Fair Value Measurements) (Details) (Collar [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Collar [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Beginning of period	$ (2,595)		$ (595)
Included in earnings	(3,428)	[1]	(1,941)
Included in other comprehensive income (loss)	0		0
Settlements	1,559		0
End of period	(4,464)		(2,536)
Total losses for the period included in earnings attributable to the change in unrealized loss relating to assets still held at end of period	$ (1,869)		$ (1,941)

[1] Commodity collars are reported in the Unaudited Condensed Consolidated Statements of Income in oil and natural gas revenues (for cash flow hedges) and loss on derivatives not designated as hedges and hedge ineffectiveness, net, respectively.