Investments In and Advances To Affiliates - Summary of Financial Information of Affiliates & Subsidiaries (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments in and Advances to Affiliates [Line Items]
Revenue									$ 15,891	$ 17,164	$ 16,098
Operating margin	670	927	901	749	882	964	693	1,044	3,247	3,583	4,040
Net income (loss)	(204)	223	333	199	323	(1,402)	207	515	551	(357)	1,530
Current assets	7,739				8,465				7,739	8,465
Current liabilities	7,653				8,319				7,653	8,319
Noncurrent liabilities	25,029				25,919				25,029	25,919
Noncontrolling interests	3,321				2,945				3,321	2,945
Stockholders’ equity	4,330				4,569				4,330	4,569
Undistributed earnings of minority-owned affiliates	168								168
Distributions received from minority-owned affiliates									6	22	36
Basis difference between carrying amount and investment	214								214
Minority Owned Affiliates
Investments in and Advances to Affiliates [Line Items]
Revenue									1,099	1,868	1,668
Operating margin									295	355	258
Net income (loss)									53	146	(5)
Current assets	842				1,097				842	1,097
Noncurrent assets	3,722				5,253				3,722	5,253
Current liabilities	600				680				600	680
Noncurrent liabilities	2,096				2,899				2,096	2,899
Noncontrolling interests	15				(228)				15	(228)
Stockholders’ equity	1,853				2,999				1,853	2,999
Majority Owned Affiliates
Investments in and Advances to Affiliates [Line Items]
Revenue									2	106	24
Operating margin									0	26	24
Net income (loss)									0	(5)	(5)
Current assets	1				2				1	2
Noncurrent assets	20				38				20	38
Current liabilities	1				55				1	55
Noncurrent liabilities	75				20				75	20
Noncontrolling interests	0				0				0	0
Stockholders’ equity	$ (55)				$ (35)				$ (55)	$ (35)