Employee Benefit Plans, Amounts Recognized in Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net loss (gain) arising during the year:
Net actuarial loss (gain)	$ 228	$ 285	$ 40
Prior service cost (credit)	9	4	(31)
Net gain (loss) reclassified into income:
Net actuarial loss	(34)	(14)	(6)
Prior service (cost) credit	20	21	17
Curtailment and settlement	(12)	(4)	(4)
Net loss on pension and other postretirement benefits	211	292	16
Pension Plans [Member]
Net loss (gain) arising during the year:
Net actuarial loss (gain)	245	294	68
Prior service cost (credit)	9	4	0
Net gain (loss) reclassified into income:
Net actuarial loss	(33)	(12)	(2)
Prior service (cost) credit	(3)	(2)	(3)
Curtailment and settlement	(12)	(4)	(4)
Net loss on pension and other postretirement benefits	206	280	59
Other Postretirement Benefit Plans [Member]
Net loss (gain) arising during the year:
Net actuarial loss (gain)	(17)	(9)	(28)
Prior service cost (credit)	0	0	(31)
Net gain (loss) reclassified into income:
Net actuarial loss	(1)	(2)	(4)
Prior service (cost) credit	23	23	20
Curtailment and settlement	0	0	0
Net loss on pension and other postretirement benefits	$ 5	$ 12	$ (43)