Benefit Plans (Schedule of estimated amounts to be recognized from Accumulated other comprehensive income into net periodic cost (benefit) during next fiscal year) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Pension Plans, Defined Benefit [Member]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year
Amortization of prior service cost (credit)
Amortization of net actuarial (gain) loss	47
Total estimated amounts to be recognized	47
Other Postretirement Benefit Plans, Defined Benefit [Member]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year
Amortization of prior service cost (credit)	(18)
Amortization of net actuarial (gain) loss	1
Total estimated amounts to be recognized	$ (17)