Segments and Geographic Information Segment and Geographic Information (Revenue and Assets by Country) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue		$ 2,431	$ 2,625	$ 2,483	$ 2,650	$ 2,622	$ 2,837	$ 2,537	$ 2,740	$ 10,189	$ 10,736	$ 10,530
Property, plant and equipment, net		22,574				21,396				22,574	21,396
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	[1]									3,230	3,462	3,487
Property, plant and equipment, net	[1]	9,706				8,731				9,706	8,731
Total Non-U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										6,959	7,274	7,043
Property, plant and equipment, net		12,868				12,665				12,868	12,665
PHILIPPINES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	[2]									0	93	449
Property, plant and equipment, net	[2]	0				0				0	0
Brazil
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										525	527	541
Property, plant and equipment, net		1,260				1,287				1,260	1,287
CHILE
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										1,839	2,087	1,944
Property, plant and equipment, net		5,939				5,453				5,939	5,453
Dominican Republic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										877	884	826
Property, plant and equipment, net		1,002				903				1,002	903
El Salvador
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										824	768	686
Property, plant and equipment, net		343				334				343	334
Colombia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										472	428	332
Property, plant and equipment, net		340				302				340	302
ARGENTINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										373	487	435
Property, plant and equipment, net		392				234				392	234
Vietnam
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	[3]									343	245	278
Property, plant and equipment, net	[3]	2				2				2	2
Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										402	399	352
Property, plant and equipment, net		648				666				648	666
UNITED KINGDOM
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	[4]									147	390	328
Property, plant and equipment, net	[4]	0				90				0	90
BULGARIA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										459	426	367
Property, plant and equipment, net		1,104				1,183				1,104	1,183
Panama
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										601	438	338
Property, plant and equipment, net		1,819				1,777				1,819	1,777
Puerto Rico
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	[1]									294	257	247
Property, plant and equipment, net	[1]	538				553				538	553
JORDAN
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	[5]									95	95	95
Property, plant and equipment, net	[5]	0				418				0	418
KAZAKHSTAN
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										0	0	67
Property, plant and equipment, net		0				0				0	0
Other Non-U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue										2	7	$ 5
Property, plant and equipment, net		$ 19				$ 16				$ 19	$ 16

[1] Includes Puerto Rico revenues of $294 million, $257 million and $247 million for the years ended December 31, 2019, 2018 and 2017, respectively, and property, plant & equipment of $538 million and $553 million as of December 31, 2019 and 2018, respectively.

[2] The Masinloc property, plant and equipment was classified as held-for-sale as of December 31, 2017, and deconsolidated upon completion of the sale in March 2018. See Note 25—Held-For-Sale and Dispositions for further information.

[3] The Mong Duong II power project is operated under a build, operate and transfer contract. Future expected payments for the construction performance obligation are recognized in Loan receivable on the Consolidated Balance Sheets. See Note 20—Revenue for further information.

[4] The Kilroot and Ballylumford property, plant and equipment was deconsolidated upon completion of the sale in June 2019. See Note 25—Held-For-Sale and Dispositions for further information.

[5] The property, plant and equipment in Jordan was classified as held-for-sale as of December 31, 2019. See Note 25—Held-For-Sale and Dispositions for further information.