Pension and Other Postretirement Benefits Pension and Other Postretirement Benefits-Projected Benefit Obligation (Details) (Other Postretirement Benefit Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Accumulated Benefit Obligation, Continuing and Discontinued Operations, beginning of year	$ 195	$ 184
Service Cost, Continuing and Discontinued Operations	1	1
Interest Cost, Continuing and Discontinued Operations	7	9
Actuarial Losses, Continuing and Discontinued Operations	(26)	(13)
Benefits Paid, Continuing and Discontinued Operations	21	12
Curtailments, Continuing and Discontinued Operations	11	0
Accumulated Benefit Obligation, Continuing and Discontinued Operations, end of year	$ 197	$ 195