Employee Benefit Plans, Amounts Recognized in Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Plans [Member]
Net (gain) loss arising during the year:
Net actuarial loss (gain)	$ 294	$ 68	$ (273)
Prior service credit	4	0	0
Net gain (loss) reclassified into income:
Net actuarial loss	(12)	(2)	(10)
Prior service (cost) credit	(2)	(3)	(3)
Curtailment and settlement	(4)	(4)	(1)
Total changes in other comprehensive (income) loss	280	59	(287)
Other Postretirement Benefit Plans [Member]
Net (gain) loss arising during the year:
Net actuarial loss (gain)	(9)	(28)	(27)
Prior service credit	0	(31)	(51)
Net gain (loss) reclassified into income:
Net actuarial loss	(2)	(4)	(6)
Prior service (cost) credit	23	20	19
Curtailment and settlement	0	0	0
Total changes in other comprehensive (income) loss	$ 12	$ (43)	$ (65)