Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating Leases, Rent Expense	$ 295	$ 297	$ 303
Letters of Credit Outstanding, Amount	72
Surety bonds outstanding	316
California Claims Processing Matter [Member]
Total number of violations alleged by CDI (violations)	919,574	992,936
CDI aggregate penalty	325
Largest aggregate penalty issued by CDI	8
Maximum fine per CDI violation (dollars per violation)	10,000
Average penalty per alleged violation (dollars per violation)	326
Guaranty Fund Assessments [Member]
Estimated potential range of loss, amount, minimum	250
Estimated potential range of loss, amount, maximum	$ 350