Fair Value (Level 3 Reconciliation) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	$ 14	$ (4)	$ (4)	$ (341)
Total gains (losses) (realized and unrealized):
Included in earnings	13	9	39	12
Included in other comprehensive income - derivative activity	(30)	13	(100)	81
Included in other comprehensive income - foreign currency translation activity	(2)	(3)	(20)	(4)
Included in regulatory (assets) liabilities	15	11	12	10
Settlements	(1)	3	12	45
Transfers of assets (liabilities) into Level 3	(69)	(42)
Transfers of (assets) liabilities out of Level 3	0	29	1	213
Balance at the end of the period	(60)	16	(60)	16
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	9	14	35	14
Interest Rate [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	(87)	(72)	(101)	(412)
Total gains (losses) (realized and unrealized):
Included in earnings	0	(4)	1	(4)
Included in other comprehensive income - derivative activity	(30)	13	(99)	81
Included in other comprehensive income - foreign currency translation activity	0	0	0	2
Included in regulatory (assets) liabilities	0	0	0	0
Settlements	3	4	16	48
Transfers of assets (liabilities) into Level 3	(69)	(42)
Transfers of (assets) liabilities out of Level 3	0	38	0	222
Balance at the end of the period	(183)	(63)	(183)	(63)
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	101	71	93	72
Total gains (losses) (realized and unrealized):
Included in earnings	10	12	37	15
Included in other comprehensive income - derivative activity	0	0	(1)	0
Included in other comprehensive income - foreign currency translation activity	(2)	(3)	(20)	(6)
Included in regulatory (assets) liabilities	0	0	0	0
Settlements	(2)	(1)	(3)	(2)
Transfers of assets (liabilities) into Level 3	0	0
Transfers of (assets) liabilities out of Level 3	0	(9)	1	(9)
Balance at the end of the period	107	70	107	70
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	9	14	34	13
Commodity [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	0	(3)	4	(1)
Total gains (losses) (realized and unrealized):
Included in earnings	3	1	1	1
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	15	11	12	10
Settlements	(2)	0	(1)	(1)
Transfers of assets (liabilities) into Level 3	0	0
Transfers of (assets) liabilities out of Level 3	0	0	0	0
Balance at the end of the period	16	9	16	9
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	$ 0	$ 1