v3.19.1

Variable Interest Entities and Unconsolidated Investments in Power Plants (VIE Texuals) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) yr MW	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) MW
Variable Interest Entity [Line Items]
Variable interest entity, financial or other support, amount	$ 0	$ 0
Equity method investment, ownership percentage	50.00%
Equity method investment, summarized financial information, debt	$ 302		$ 301
Prorata share of equity method investment, summarized financial information, debt	151		$ 151
Return on investments from unconsolidated subsidiaries	$ 11	3
Greenfield [Member]
Variable Interest Entity [Line Items]
Power generation capacity | MW	1,038
Equity method investment, ownership percentage	50.00%
Return on investments from unconsolidated subsidiaries	$ 0	0
Whitby [Member]
Variable Interest Entity [Line Items]
Power generation capacity | MW	50
Equity method investment, ownership percentage	50.00%
Return on investments from unconsolidated subsidiaries	$ 11	$ 3
Calpine Receivables [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 60
Equity method investment, ownership percentage	100.00%
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Power generation capacity | MW	7,880		7,880
Put Option [Member]
Variable Interest Entity [Line Items]
Proceeds from sale of property, plant and equipment	$ 280
Call Option [Member]
Variable Interest Entity [Line Items]
Proceeds from sale of property, plant and equipment	$ 377
Inland Empire Energy Center [Member]
Variable Interest Entity [Line Items]
Power generation capacity | MW	775
Put Option Exercise Period | yr	2,025
Inland Empire Energy Center [Member] | Minimum [Member]
Variable Interest Entity [Line Items]
Call Option Exercise Period | yr	2,017
Inland Empire Energy Center [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Call Option Exercise Period | yr	2,024
OMEC [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	$ 220

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