Derivative Instruments and Hedging Activities - Part 2 (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Assets
Derivative Assets, Gross	$ 198	$ 100
Liabilities
Derivative Liabilities, Gross	396	602
Subject to netting arrangement [Member]
Assets
Derivative Assets, Gross	79	25
Derivative Assets Not Offset Under Netting Arrangements	(11)	(9)
Derivative Assets Not Offset By Collateral	0	0
Derivative Assets, Net	68	16
Liabilities
Derivative Liabilities, Gross	368	522
Derivative Liabilities Not Offset Under Netting Arrangements	(11)	(9)
Derivative Liabilities Not Offset By Collateral	(4)	(5)
Derivative Liabilities, Net	353	508
Current [Member]
Assets
Derivative Assets, Gross	36	14
Liabilities
Derivative Liabilities, Gross	136	178
Noncurrent [Member]
Assets
Derivative Assets, Gross	162	86
Liabilities
Derivative Liabilities, Gross	260	424
Designated as Hedging Instruments [Member]
Assets
Derivative Assets, Gross	62	8
Liabilities
Derivative Liabilities, Gross	364	565
Not Designated as Hedging Instruments [Member]
Assets
Derivative Assets, Gross	136	92
Liabilities
Derivative Liabilities, Gross	32	37
No longer carried at fair value [Member]
Assets
Derivative Assets, Gross	173	186
Liabilities
Derivative Liabilities, Gross	190	191
Interest rate derivatives [Member]
Assets
Derivative Assets, Gross	44	2
Liabilities
Derivative Liabilities, Gross	352	565
Interest rate derivatives [Member] | Designated as Hedging Instruments [Member]
Assets
Derivative Assets, Gross	42	0
Liabilities
Derivative Liabilities, Gross	338	544
Interest rate derivatives [Member] | Not Designated as Hedging Instruments [Member]
Assets
Derivative Assets, Gross	2	2
Liabilities
Derivative Liabilities, Gross	14	21
Cross currency derivatives [Member]
Assets
Derivative Assets, Gross	6	6
Liabilities
Derivative Liabilities, Gross	3	6
Cross currency derivatives [Member] | Designated as Hedging Instruments [Member]
Assets
Derivative Assets, Gross	6	6
Liabilities
Derivative Liabilities, Gross	3	6
Cross currency derivatives [Member] | Not Designated as Hedging Instruments [Member]
Assets
Derivative Assets, Gross	0	0
Liabilities
Derivative Liabilities, Gross	0	0
Foreign currency derivatives [Member]
Assets
Derivative Assets, Gross	114	81
Liabilities
Derivative Liabilities, Gross	21	14
Foreign currency derivatives [Member] | Designated as Hedging Instruments [Member]
Assets
Derivative Assets, Gross	6	0
Liabilities
Derivative Liabilities, Gross	13	7
Foreign currency derivatives [Member] | Not Designated as Hedging Instruments [Member]
Assets
Derivative Assets, Gross	108	81
Liabilities
Derivative Liabilities, Gross	8	7
Commodity derivatives [Member]
Assets
Derivative Assets, Gross	34	11
Liabilities
Derivative Liabilities, Gross	20	17
Commodity derivatives [Member] | Designated as Hedging Instruments [Member]
Assets
Derivative Assets, Gross	8	2
Liabilities
Derivative Liabilities, Gross	10	8
Commodity derivatives [Member] | Not Designated as Hedging Instruments [Member]
Assets
Derivative Assets, Gross	26	9
Liabilities
Derivative Liabilities, Gross	$ 10	$ 9