Segments and Geographic Information Segment and Geographic Information (Assets, Depreciation and Amortization and Capital Expenditures ) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total Assets	$ 32,521	$ 33,112	$ 36,124
Depreciation and Amortization	1,003	1,169	1,176
Capital Expenditures	2,396	2,356	2,458
Interest Income	310	244	245
Interest Expense	1,056	1,170	1,134
Investments in and Advances to Affiliates	1,114	1,197	621
Net Equity in Earnings of Affiliates	39	71	36
Operating Segments [Member] | US and Utilities SBU
Segment Reporting Information [Line Items]
Total Assets	12,286	11,548	10,815
Depreciation and Amortization	449	487	519
Capital Expenditures	1,373	905	858
Interest Income	10	5	4
Interest Expense	287	315	299
Investments in and Advances to Affiliates	538	535	23
Net Equity in Earnings of Affiliates	35	41	9
Operating Segments [Member] | Andes SBU
Segment Reporting Information [Line Items]
Total Assets	10,941	11,126	10,487
Depreciation and Amortization	300	301	251
Capital Expenditures	662	477	569
Interest Income	92	95	95
Interest Expense	283	297	247
Investments in and Advances to Affiliates	213	358	363
Net Equity in Earnings of Affiliates	15	28	15
Operating Segments [Member] | MCAC SBU
Segment Reporting Information [Line Items]
Total Assets	4,462	4,087	3,680
Depreciation and Amortization	141	122	117
Capital Expenditures	302	435	431
Interest Income	20	13	7
Interest Expense	124	111	100
Investments in and Advances to Affiliates	5	(5)	(1)
Net Equity in Earnings of Affiliates	(7)	(4)	(2)
Operating Segments [Member] | EURASIA [Member]
Segment Reporting Information [Line Items]
Total Assets	4,538	6,002	5,777
Depreciation and Amortization	99	127	149
Capital Expenditures	51	211	279
Interest Income	186	130	139
Interest Expense	145	167	179
Investments in and Advances to Affiliates	293	307	236
Net Equity in Earnings of Affiliates	14	9	13
Segment Reconciling Items [Member] | Assets held-for-sale
Segment Reporting Information [Line Items]
Total Assets	0	86	4,936
Depreciation and Amortization	0	123	128
Capital Expenditures	0	315	303
Corporate, Non-Segment [Member] | Corporate, Other and Eliminations
Segment Reporting Information [Line Items]
Total Assets	294	263	429
Depreciation and Amortization	14	9	12
Capital Expenditures	8	13	18
Interest Income	2	1	0
Interest Expense	217	280	309
Investments in and Advances to Affiliates	65	2	0
Net Equity in Earnings of Affiliates	$ (18)	$ (3)	$ 1