Fair Value (Level 3 Reconciliation) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	$ (60)	$ 16	$ (4)	$ (341)
Total gains (losses) (realized and unrealized):
Included in earnings	(7)	26	32	38
Included in other comprehensive income - derivative activity	(13)	7	(114)	84
Included in other comprehensive income - foreign currency translation activity	5	(7)	(15)	(15)
Included in regulatory (assets) liabilities	(4)	(4)	7	5
Settlements	6	8	18	70
Transfers of assets (liabilities) into Level 3		(84)
Transfers of (assets) liabilities out of Level 3		30	3	151
Balance at the end of the period	(73)	(8)	(73)	(8)
Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets and liabilities held at the end of the period	(8)	26	28	40
Interest Rate [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	(183)	(63)	(101)	(412)
Total gains (losses) (realized and unrealized):
Included in earnings	0	(1)	1	(2)
Included in other comprehensive income - derivative activity	(13)	7	(112)	84
Included in other comprehensive income - foreign currency translation activity	9	(1)	9	(3)
Included in regulatory (assets) liabilities	0	0	0	0
Settlements	7	9	23	73
Transfers of assets (liabilities) into Level 3		(84)
Transfers of (assets) liabilities out of Level 3		30	0	157
Balance at the end of the period	(180)	(103)	(180)	(103)
Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets and liabilities held at the end of the period	0	0	1	0
Foreign currency derivatives [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	107	70	93	72
Total gains (losses) (realized and unrealized):
Included in earnings	(7)	28	29	40
Included in other comprehensive income - derivative activity	0	0	(2)	0
Included in other comprehensive income - foreign currency translation activity	(4)	(6)	(24)	(12)
Included in regulatory (assets) liabilities	0	0	0	0
Settlements	(1)	(1)	(4)	(3)
Transfers of assets (liabilities) into Level 3		0
Transfers of (assets) liabilities out of Level 3		0	3	(6)
Balance at the end of the period	95	91	95	91
Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets and liabilities held at the end of the period	(8)	27	26	40
Commodity [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	16	9	4	(1)
Total gains (losses) (realized and unrealized):
Included in earnings	0	(1)	2	0
Included in other comprehensive income - derivative activity	0	0	0	0
Included in other comprehensive income - foreign currency translation activity	0	0	0	0
Included in regulatory (assets) liabilities	(4)	(4)	7	5
Settlements	0	0	(1)	0
Transfers of assets (liabilities) into Level 3		0
Transfers of (assets) liabilities out of Level 3		0	0	0
Balance at the end of the period	12	4	12	4
Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets and liabilities held at the end of the period	$ 0	$ (1)	$ 1	$ 0