Derivative Instruments and Hedging Activities - Part 2 (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Assets
Derivative Assets, Gross	$ 105	$ 100
Liabilities
Derivative Liabilities, Gross	655	657
Subect to netting arrangement
Assets
Derivative Assets, Gross	19	25
Derivative Assets, Net	11	16
Derivative Assets Not Offset By Collateral	0	0
Derivative Assets Not Offset Under Netting Arrangements	(8)	(9)
Liabilities
Derivative Liabilities, Gross	520	522
Derivative Liabilities, Net	498	508
Derivative Liabilities Not Offset By Collateral	(14)	(5)
Derivative Liabilities Not Offset Under Netting Arrangements	(8)	(9)
Noncurrent
Assets
Derivative Assets, Gross	87	86
Liabilities
Derivative Liabilities, Gross	480	471
Current
Assets
Derivative Assets, Gross	18	14
Liabilities
Derivative Liabilities, Gross	175	186
Designated as Hedging Instruments
Assets
Derivative Assets, Gross	9	8
Liabilities
Derivative Liabilities, Gross	544	565
Not Designated as Hedging Instruments
Assets
Derivative Assets, Gross	96	92
Liabilities
Derivative Liabilities, Gross	111	92
No longer carried at fair value
Assets
Derivative Assets, Gross	181	186
Liabilities
Derivative Liabilities, Gross	191	191
Interest Rate Derivatives
Assets
Derivative Assets, Gross	2	2
Liabilities
Derivative Liabilities, Gross	541	565
Interest Rate Derivatives | Designated as Hedging Instruments
Assets
Derivative Assets, Gross	0	0
Liabilities
Derivative Liabilities, Gross	523	544
Interest Rate Derivatives | Not Designated as Hedging Instruments
Assets
Derivative Assets, Gross	2	2
Liabilities
Derivative Liabilities, Gross	18	21
Cross Currency Swaps
Assets
Derivative Assets, Gross	8	6
Liabilities
Derivative Liabilities, Gross	3	6
Cross Currency Swaps | Designated as Hedging Instruments
Assets
Derivative Assets, Gross	8	6
Liabilities
Derivative Liabilities, Gross	3	6
Cross Currency Swaps | Not Designated as Hedging Instruments
Assets
Derivative Assets, Gross	0	0
Liabilities
Derivative Liabilities, Gross	0	0
Foreign Currency
Assets
Derivative Assets, Gross	88	81
Liabilities
Derivative Liabilities, Gross	18	14
Foreign Currency | Designated as Hedging Instruments
Assets
Derivative Assets, Gross	1	0
Liabilities
Derivative Liabilities, Gross	7	7
Foreign Currency | Not Designated as Hedging Instruments
Assets
Derivative Assets, Gross	87	81
Liabilities
Derivative Liabilities, Gross	11	7
Commodity & Other
Assets
Derivative Assets, Gross	7	11
Liabilities
Derivative Liabilities, Gross	93	72
Commodity & Other | Designated as Hedging Instruments
Assets
Derivative Assets, Gross	0	2
Liabilities
Derivative Liabilities, Gross	11	8
Commodity & Other | Not Designated as Hedging Instruments
Assets
Derivative Assets, Gross	7	9
Liabilities
Derivative Liabilities, Gross	$ 82	$ 64