Employee Benefit Plans (Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Loss (Income) on a Pre-tax Basis) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension
Net loss (gain)	$ 416	$ (401)	$ 34
Prior service cost (credit)	3	2	0
Amortization of prior service credit	0	0	54
Amortization of net loss	(27)	(18)	(27)
Total recognized in other comprehensive loss (income)	392	(417)	61
Postretirement
Net loss (gain)	16	(5)	2
Prior service cost (credit)	0	0	(54)
Amortization of prior service credit	14	14	7
Amortization of net loss	(2)	(2)	(1)
Total recognized in other comprehensive loss (income)	$ 28	$ 7	$ (46)