Merger and Restructuring Charges (Summary Of Merger And Restructuring Charges) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			18 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]
Merger and restructuring charges, expected cost	$ 110
Merger and restructuring charges, incurred to date cost				110
Merger and restructuring charges, incurred current period cost	35	75	0
Facilities and contract termination charges
Restructuring Cost and Reserve [Line Items]
Merger and restructuring charges, expected cost	47
Merger and restructuring charges, incurred to date cost				47
Merger and restructuring charges, incurred current period cost	31	16
Systems integration and related charges
Restructuring Cost and Reserve [Line Items]
Merger and restructuring charges, expected cost	29
Merger and restructuring charges, incurred to date cost				29
Merger and restructuring charges, incurred current period cost	3	26
Severance and other employee-related charges
Restructuring Cost and Reserve [Line Items]
Merger and restructuring charges, expected cost	26
Merger and restructuring charges, incurred to date cost				26
Merger and restructuring charges, incurred current period cost	1	25
Transaction costs
Restructuring Cost and Reserve [Line Items]
Merger and restructuring charges, expected cost	8
Merger and restructuring charges, incurred to date cost				8
Merger and restructuring charges, incurred current period cost	$ 0	$ 8