Fair Value Measurements (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Available-for-sale investments:
Available-for-sale investments	$ 117	$ 139
Derivative instruments:
Total derivative assets	4,001	3,219
Subtotal	3,143	2,437
Net derivative assets	2,140	1,551
Total	2,257	1,690
Quoted prices in active markets (Level 1) [Member]
Available-for-sale investments:
Available-for-sale investments	20	39
Derivative instruments:
Total derivative assets	0	0
Total	20	39
Quoted prices in active markets (Level 1) [Member] | US Treasury Securities [Member]
Available-for-sale investments:
Available-for-sale investments	20	39
Quoted prices in active markets (Level 1) [Member] | Agency residential mortgage backed securities [Member]
Available-for-sale investments:
Available-for-sale investments	0	0
Quoted prices in active markets (Level 1) [Member] | Guaranteed investment contracts [Member]
Available-for-sale investments:
Available-for-sale investments	0	0
Quoted prices in active markets (Level 1) [Member] | Other [Member]
Available-for-sale investments:
Available-for-sale investments	0	0
Derivative instruments:
Total derivative assets	0
Quoted prices in active markets (Level 1) [Member] | Interest rate swaps [Member]
Derivative instruments:
Total derivative assets	0	0
Quoted prices in active markets (Level 1) [Member] | Cross currency interest rate swaps [Member]
Derivative instruments:
Total derivative assets	0	0
Quoted prices in active markets (Level 1) [Member] | Other [Member]
Derivative instruments:
Total derivative assets		0
Other Observable Inputs (Level 2) [Member]
Available-for-sale investments:
Available-for-sale investments	97	100
Derivative instruments:
Total derivative assets	1,458	1,444
Total	1,555	1,544
Other Observable Inputs (Level 2) [Member] | US Treasury Securities [Member]
Available-for-sale investments:
Available-for-sale investments	0	0
Other Observable Inputs (Level 2) [Member] | Agency residential mortgage backed securities [Member]
Available-for-sale investments:
Available-for-sale investments	64	68
Other Observable Inputs (Level 2) [Member] | Guaranteed investment contracts [Member]
Available-for-sale investments:
Available-for-sale investments	21	20
Other Observable Inputs (Level 2) [Member] | Other [Member]
Available-for-sale investments:
Available-for-sale investments	12	12
Derivative instruments:
Total derivative assets	0
Other Observable Inputs (Level 2) [Member] | Interest rate swaps [Member]
Derivative instruments:
Total derivative assets	1,011	1,017
Other Observable Inputs (Level 2) [Member] | Cross currency interest rate swaps [Member]
Derivative instruments:
Total derivative assets	447	427
Other Observable Inputs (Level 2) [Member] | Other [Member]
Derivative instruments:
Total derivative assets		0
Unobservable Inputs (Level 3) [Member]
Available-for-sale investments:
Available-for-sale investments	0	0
Derivative instruments:
Total derivative assets	2,543	1,775
Total	2,543	1,775
Unobservable Inputs (Level 3) [Member] | US Treasury Securities [Member]
Available-for-sale investments:
Available-for-sale investments	0	0
Unobservable Inputs (Level 3) [Member] | Agency residential mortgage backed securities [Member]
Available-for-sale investments:
Available-for-sale investments	0	0
Unobservable Inputs (Level 3) [Member] | Guaranteed investment contracts [Member]
Available-for-sale investments:
Available-for-sale investments	0	0
Unobservable Inputs (Level 3) [Member] | Other [Member]
Available-for-sale investments:
Available-for-sale investments	0	0
Derivative instruments:
Total derivative assets	3	26
Unobservable Inputs (Level 3) [Member] | Interest rate swaps [Member]
Derivative instruments:
Total derivative assets	119	150
Unobservable Inputs (Level 3) [Member] | Cross currency interest rate swaps [Member]
Derivative instruments:
Total derivative assets	2,421	1,599
US Treasury Securities [Member]
Available-for-sale investments:
Available-for-sale investments	20	39
Agency residential mortgage backed securities [Member]
Available-for-sale investments:
Available-for-sale investments	64	68
Guaranteed investment contracts [Member]
Available-for-sale investments:
Available-for-sale investments	21	20
Other [Member]
Available-for-sale investments:
Available-for-sale investments	12	12
Interest rate swaps [Member]
Derivative instruments:
Total derivative assets	1,130	1,167
Cross currency interest rate swaps [Member]
Derivative instruments:
Total derivative assets	2,868	2,026
Other [Member]
Derivative instruments:
Total derivative assets	3	26
Counterparty Netting [Member]
Derivative instruments:
Net derivative assets	(858)	(782)
Cash collateral held [Member]
Derivative instruments:
Net derivative assets	$ (1,003)	$ (886)