Employee Benefit Plans (Share-Based Compensation Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Dec. 31, 2011
Employee Benefit Plans [Abstract]
Share-based compensation expense	$ 15	[1]	$ 13	[1]
Unrecognized share-based compensation expense	49				43
Expense recognized in integration-related costs	$ 4		$ 3

[1] Includes $4 million and $3 million of expense recognized in integration-related costs for three months ended March 31, 2012 and 2011, respectively.