Variable Interest Entities and Unconsolidated Investments in Power Plants (Income from Unconsolidated Investments 10-Q) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
(Income) from unconsolidated subsidiaries	$ (5)	$ (5)	$ (11)	$ (11)
Greenfield [Member]
(Income) from unconsolidated subsidiaries	(4)	(2)	(6)	(4)
Whitby [Member]
(Income) from unconsolidated subsidiaries	(2)	(4)	(6)	(8)
Calpine Receivables [Member]
(Income) from unconsolidated subsidiaries	$ 1	$ 1	$ 1	$ 1

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

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