Variable Interest Entities and Unconsolidated Investments in Power Plants (Income from Unconsolidated Investments 10-Q) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
(Income) from unconsolidated subsidiaries	$ (3)	$ (5)	$ (14)	$ (16)
Greenfield [Member]
(Income) from unconsolidated subsidiaries	(4)	(2)	(10)	(6)
Whitby [Member]
(Income) from unconsolidated subsidiaries	1	(3)	(5)	(11)
Calpine Receivables [Member]
(Income) from unconsolidated subsidiaries	$ 0	$ 0	$ 1	$ 1

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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