Acquisition (Summary Of Merger And Restructuring Charges) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Merger and restructuring charges, expected cost	$ 115
Merger and restructuring charges, incurred cost	75	0	0
Facilities and Contract Terminations [Member]
Merger and restructuring charges, expected cost	55
Merger and restructuring charges, incurred cost	16
Systems Integration and Related [Member]
Merger and restructuring charges, expected cost	27
Merger and restructuring charges, incurred cost	26
Severance and Other Employee-Related Charges [Member]
Merger and restructuring charges, expected cost	25
Merger and restructuring charges, incurred cost	25
Transaction Costs [Member]
Merger and restructuring charges, expected cost	8
Merger and restructuring charges, incurred cost	$ 8