Employee Benefit Plans (Details 7) (USD $) In Millions, unless otherwise specified	12 Months Ended							12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Corporate [Member]	Dec. 31, 2010 Corporate [Member]	Dec. 31, 2011 Mortgage Backed Securities [Member]	Dec. 31, 2010 Mortgage Backed Securities [Member]	Dec. 31, 2009 Mortgage Backed Securities [Member]	Dec. 31, 2011 Real Estate [Member]	Dec. 31, 2010 Real Estate [Member]	Dec. 31, 2011 Other Plan Assets [Member]	Dec. 31, 2010 Other Plan Assets [Member]
The effect of fair-value measurements using significant unobservable inputs on changes in Level 3 plan assets for the period are outlined below
Beginning Balance	$ 823	$ 682	$ 28	$ 18	$ 2	$ 2	$ 2	$ 738	$ 610	$ 55	$ 52
Actual Return on Plan Assets
Assets held at the reporting date	107	38		3				103	34	4	1
Assets sold during the period	(1)	1						1	1	(2)
Purchases, Sales and Settlements	154	102	(1)	7				156	93	(1)	2
Ending Balance	$ 1,083	$ 823	$ 27	$ 28	$ 2	$ 2	$ 2	$ 998	$ 738	$ 56	$ 55