Revenue From Contracts with Customers Disaggregation of Revenues (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Commodity revenue		$ 1,852		$ 2,128		$ 3,795		$ 4,666
Other income		1				2
Revenues		1,744	[1]	2,599	[1]	4,036	[2]	5,198	[2]
West
Disaggregation of Revenue [Line Items]
Revenues		470	[1]	649	[1]	1,175	[2]	1,331	[2]
Texas
Disaggregation of Revenue [Line Items]
Revenues		620	[1]	899	[1]	1,270	[2]	1,642	[2]
East
Disaggregation of Revenue [Line Items]
Revenues		244	[1]	646	[1]	786	[2]	1,335	[2]
Retail
Disaggregation of Revenue [Line Items]
Revenues		720	[1]	1,082	[1]	1,628	[2]	2,080	[2]
Energy & other products
Disaggregation of Revenue [Line Items]
Commodity revenue		838		1,000		1,688		2,209
Energy & other products | West
Disaggregation of Revenue [Line Items]
Commodity revenue		163		145		364		437
Energy & other products | Texas
Disaggregation of Revenue [Line Items]
Commodity revenue		254		318		473		620
Energy & other products | East
Disaggregation of Revenue [Line Items]
Commodity revenue		99		124		205		327
Energy & other products | Retail
Disaggregation of Revenue [Line Items]
Commodity revenue		322		413		646		825
Energy & other products | Elimination
Disaggregation of Revenue [Line Items]
Commodity revenue		0		0		0		0
Capacity
Disaggregation of Revenue [Line Items]
Commodity revenue		198		223		393		467
Capacity | West
Disaggregation of Revenue [Line Items]
Commodity revenue		66		36		128		71
Capacity | Texas
Disaggregation of Revenue [Line Items]
Commodity revenue		28		33		56		65
Capacity | East
Disaggregation of Revenue [Line Items]
Commodity revenue		104		154		209		331
Capacity | Retail
Disaggregation of Revenue [Line Items]
Commodity revenue		0		0		0		0
Capacity | Elimination
Disaggregation of Revenue [Line Items]
Commodity revenue		0		0		0		0
Revenues relating to physical or executory contracts – third party
Disaggregation of Revenue [Line Items]
Commodity revenue		1,036		1,223		2,081		2,676
Revenues relating to physical or executory contracts – third party | West
Disaggregation of Revenue [Line Items]
Commodity revenue		229		181		492		508
Revenues relating to physical or executory contracts – third party | Texas
Disaggregation of Revenue [Line Items]
Commodity revenue		282		351		529		685
Revenues relating to physical or executory contracts – third party | East
Disaggregation of Revenue [Line Items]
Commodity revenue		203		278		414		658
Revenues relating to physical or executory contracts – third party | Retail
Disaggregation of Revenue [Line Items]
Commodity revenue		322		413		646		825
Revenues relating to physical or executory contracts – third party | Elimination
Disaggregation of Revenue [Line Items]
Commodity revenue		0		0		0		0
Affiliate Revenue
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	0		0		0		0
Affiliate Revenue | West
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	9		6		26		17
Affiliate Revenue | Texas
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	10		14		20		28
Affiliate Revenue | East
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	20		30		39		57
Affiliate Revenue | Retail
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	2		1		3		4
Affiliate Revenue | Elimination
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	(41)		(51)		(88)		(106)
Revenues relating to leases and derivative instruments
Disaggregation of Revenue [Line Items]
Revenues		$ 707	[4]	$ 1,376	[4]	$ 1,953	[4]	$ 2,522

[1] Includes intersegment revenues of $70 million and $100 million in the West, $214 million and $348 million in Texas, $24 million and $228 million in the East and $2 million and $1 million in Retail for the three months ended June 30, 2020 and 2019, respectively.

[2] Includes intersegment revenues of $189 million and $262 million in the West, $432 million and $559 million in Texas, $199 million and $365 million in the East and $3 million and $4 million in Retail for the six months ended June 30, 2020 and 2019, respectively.

[3] Affiliate energy, other and capacity revenues reflect revenues on transactions between wholesale and retail affiliates excluding affiliate activity related to leases and derivative instruments. All such activity supports retail supply needs from the wholesale business and/or allows for collateral margin netting efficiencies at Calpine.

[4] Revenues relating to contracts accounted for as leases and derivatives include energy and capacity revenues relating to PPAs that we are required to account for as operating leases and physical and financial commodity derivative contracts, primarily relating to power, natural gas and environmental products. Revenue related to derivative instruments includes revenue recorded in Commodity revenue and mark-to-market gain (loss) within our operating revenues on our Consolidated Condensed Statements of Operations.