Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 segment		Mar. 31, 2013		Dec. 31, 2013
Segment Reporting Information [Line Items]
Number of strategic business units	6
Number of reportable segments	6
Revenue
Total Revenue	$ 4,262		$ 4,150
Adjusted PTC
External Adjusted Pre-tax Contribution	243	[1]	270	[1]
Reconciliation To Income From Continuing Operations Before Taxes
Unrealized derivative gains (losses)	10		(14)
Unrealized foreign currency gains (losses)	(26)		(25)
Disposition/acquisition gains	1		3
Impairment losses	(166)		(48)
Loss on extinguishment of debt	(134)		(43)
Pre-tax contribution	(72)		143
Add: income from continuing operations before taxes, attributable to noncontrolling interests	215		171
Less: Net equity in earnings of affiliates	25		4
INCOME FROM CONTINUING OPERATIONS BEFORE TAXES AND EQUITY IN EARNINGS OF AFFILIATES	118		310
US SBU
Total Assets	40,973				40,411
Operating Segments [Member]
Revenue
Total Revenue	4,265		4,151
Adjusted PTC
External Adjusted Pre-tax Contribution	243	[1]	270	[1]
Intersegment Eliminations [Member]
Revenue
Total Revenue	(3)		(1)
Adjusted PTC
External Adjusted Pre-tax Contribution	0	[1]	0	[1]
US - Generation [Member]
Revenue
Total Revenue	1,001		886
Adjusted PTC
External Adjusted Pre-tax Contribution	78	[1]	135	[1]
US SBU
Total Assets	9,813				9,952
US - Generation [Member] | Operating Segments [Member]
Revenue
Total Revenue	1,001		886
Adjusted PTC
External Adjusted Pre-tax Contribution	75	[1]	133	[1]
US - Generation [Member] | Intersegment Eliminations [Member]
Revenue
Total Revenue	0		0
Adjusted PTC
External Adjusted Pre-tax Contribution	3	[1]	2	[1]
Andes - Generation [Member]
Revenue
Total Revenue	620		690
Adjusted PTC
External Adjusted Pre-tax Contribution	56	[1]	84	[1]
US SBU
Total Assets	7,276				7,356
Andes - Generation [Member] | Operating Segments [Member]
Revenue
Total Revenue	620		690
Adjusted PTC
External Adjusted Pre-tax Contribution	53	[1]	81	[1]
Andes - Generation [Member] | Intersegment Eliminations [Member]
Revenue
Total Revenue	0		0
Adjusted PTC
External Adjusted Pre-tax Contribution	3	[1]	3	[1]
Brazil - Generation [Member]
Revenue
Total Revenue	1,445		1,429
Adjusted PTC
External Adjusted Pre-tax Contribution	70	[1]	43	[1]
US SBU
Total Assets	9,288				8,388
Brazil - Generation [Member] | Operating Segments [Member]
Revenue
Total Revenue	1,445		1,429
Adjusted PTC
External Adjusted Pre-tax Contribution	69	[1]	42	[1]
Brazil - Generation [Member] | Intersegment Eliminations [Member]
Revenue
Total Revenue	0		0
Adjusted PTC
External Adjusted Pre-tax Contribution	1	[1]	1	[1]
MCAC - Generation [Member]
Revenue
Total Revenue	637		669
Adjusted PTC
External Adjusted Pre-tax Contribution	69	[1]	59	[1]
US SBU
Total Assets	5,058				5,075
MCAC - Generation [Member] | Operating Segments [Member]
Revenue
Total Revenue	638		669
Adjusted PTC
External Adjusted Pre-tax Contribution	65	[1]	56	[1]
MCAC - Generation [Member] | Intersegment Eliminations [Member]
Revenue
Total Revenue	(1)		0
Adjusted PTC
External Adjusted Pre-tax Contribution	4	[1]	3	[1]
EMEA - Generation [Member]
Revenue
Total Revenue	391		343
Adjusted PTC
External Adjusted Pre-tax Contribution	118	[1]	99	[1]
US SBU
Total Assets	4,276				4,191
EMEA - Generation [Member] | Operating Segments [Member]
Revenue
Total Revenue	391		343
Adjusted PTC
External Adjusted Pre-tax Contribution	115	[1]	96	[1]
EMEA - Generation [Member] | Intersegment Eliminations [Member]
Revenue
Total Revenue	0		0
Adjusted PTC
External Adjusted Pre-tax Contribution	3	[1]	3	[1]
Asia - Generation [Member]
Revenue
Total Revenue	168		133
Adjusted PTC
External Adjusted Pre-tax Contribution	9	[1]	32	[1]
US SBU
Total Assets	2,920				2,810
Asia - Generation [Member] | Operating Segments [Member]
Revenue
Total Revenue	168		133
Adjusted PTC
External Adjusted Pre-tax Contribution	8	[1]	31	[1]
Asia - Generation [Member] | Intersegment Eliminations [Member]
Revenue
Total Revenue	0		0
Adjusted PTC
External Adjusted Pre-tax Contribution	1	[1]	1	[1]
Corporate Other And Other Eliminations [Member]
Revenue
Total Revenue	0		0
Adjusted PTC
External Adjusted Pre-tax Contribution	(157)	[1]	(182)	[1]
US SBU
Total Assets	752				921
Corporate Other And Other Eliminations [Member] | Operating Segments [Member]
Revenue
Total Revenue	2		1
Adjusted PTC
External Adjusted Pre-tax Contribution	(142)	[1]	(169)	[1]
Corporate Other And Other Eliminations [Member] | Intersegment Eliminations [Member]
Revenue
Total Revenue	(2)		(1)
Adjusted PTC
External Adjusted Pre-tax Contribution	(15)	[1]	(13)	[1]
Discontinued Operations [Member]
US SBU
Total Assets	$ 1,590				$ 1,718

[1] Adjusted pre-tax contribution in each segment before intersegment eliminations includes the effect of intercompany transactions with other segments except for interest, charges for certain management fees and the write-off of intercompany balances.