Commitments and Contingencies - Environmental (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended				3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Environmental Issue [Member] sites	Dec. 31, 2013 Environmental Issue [Member]	Sep. 30, 2014 Environmental Issue [Member]	Sep. 30, 2013 Environmental Issue [Member]
Loss Contingencies [Line Items]
Number of alleged environmental contamination sites (in sites)					232
Number of environmental superfund sites (in sites)					16
Liability for third-party tort claims					$ 15	$ 13
Accrued obligations for environmental matters, current liabilities	65		65
Additional environmental expense							5	12
Future costs for environmental liabilities, minimum					315
Future costs for environmental liabilities, maximum					550
Site Contingency, Estimated Time Frame for Accrued Cost Distributions			10 years
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	416	440	435	458
Accruals	8	18	13	17
Payments	(10)	(14)	(34)	(31)
Ending balance	$ 414	$ 444	$ 414	$ 444