Fair Value (Instruments Not Measured at Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Carrying Amount [Member]
Financial Instruments Not Measured At Fair Value In the Condensed Consolidated Balance Sheets [Abstract]
Accounts receivable - noncurrent	$ 210	[1]	$ 260	[1]
Recourse debt	5,347		5,669
Non-recourse debt	15,719		15,380
Fair Value [Member]
Financial Instruments Not Measured At Fair Value In the Condensed Consolidated Balance Sheets [Abstract]
Accounts receivable - noncurrent	170	[1]	194	[1]
Value added tax	36		46
Recourse debt	5,598		6,164
Non-recourse debt	16,117		15,620
Level 1 [Member] | Fair Value [Member]
Financial Instruments Not Measured At Fair Value In the Condensed Consolidated Balance Sheets [Abstract]
Accounts receivable - noncurrent	0	[1]	0	[1]
Recourse debt	0		0
Non-recourse debt	0		0
Level 2 [Member] | Fair Value [Member]
Financial Instruments Not Measured At Fair Value In the Condensed Consolidated Balance Sheets [Abstract]
Accounts receivable - noncurrent	0	[1]	0	[1]
Recourse debt	5,598		6,164
Non-recourse debt	13,818		13,397
Level 3 [Member] | Fair Value [Member]
Financial Instruments Not Measured At Fair Value In the Condensed Consolidated Balance Sheets [Abstract]
Accounts receivable - noncurrent	170	[1]	194	[1]
Recourse debt	0		0
Non-recourse debt	$ 2,299		$ 2,223

[1] These accounts receivable principally relate to amounts due from CAMMESA, the administrator of the wholesale electricity market in Argentina, and are included in “Noncurrent assets — Other” in the accompanying Condensed Consolidated Balance Sheets. The fair value and carrying amount of these accounts receivable exclude value-added tax of $36 million and $46 million at September 30, 2014 and December 31, 2013, respectively.