Variable Interest Entities and Unconsolidated Investments (Unconsolidated Investements) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Loss from Unconsolidated Investments in Power Plants and Distributions [Line Items]
(Income) from unconsolidated subsidiaries		$ (22)	$ (24)	$ (22)
Distributions from Equity Method Investments		26	53	28
Greenfield [Member]
Income Loss from Unconsolidated Investments in Power Plants and Distributions [Line Items]
(Income) from unconsolidated subsidiaries		(13)	(11)	(14)
Distributions from Equity Method Investments		0	48	8
Whitby [Member]
Income Loss from Unconsolidated Investments in Power Plants and Distributions [Line Items]
(Income) from unconsolidated subsidiaries	[1]	(11)	(15)	(10)
Distributions from Equity Method Investments	[1]	26	5	20
Calpine Receivables [Member]
Income Loss from Unconsolidated Investments in Power Plants and Distributions [Line Items]
(Income) from unconsolidated subsidiaries		2	2	2
Distributions from Equity Method Investments		$ 0	$ 0	$ 0

[1] On November 20, 2019, we sold our 50% interest in Whitby to a third party.