Segment Information (Schedule Of Revenues By Geographic Area) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) segment	Jun. 30, 2014 USD ($)
Revenues From External Customers And Long-Lived Assets [Line Items]
Number of reportable segments | segment			1
Revenues	$ 1,521	$ 1,457	$ 3,032	$ 2,817
United States
Revenues From External Customers And Long-Lived Assets [Line Items]
Revenues	742	683	1,504	1,332
International
Revenues From External Customers And Long-Lived Assets [Line Items]
Revenues	$ 779	$ 774	$ 1,528	$ 1,485