Acquisitions And Divestitures (Summary Of Consolidated Results Of Operations On Pro Forma Basis) (Details) (Chesapeake Property Acquisition [Member], USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Chesapeake Property Acquisition [Member]
Business Acquisition [Line Items]
Revenues	$ 1,251
Net Income	$ 243
Basic	$ 0.48
Diluted	$ 0.48