Revenue From Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ 2,009
Revenues	[1]	2,009	$ 2,281
Capitalized Contract Cost, Impairment Loss		0
Revenue, Remaining Performance Obligation		$ 200
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year		2029
West [Member]
Disaggregation of Revenue [Line Items]
Revenues	[1]	$ 480	519
Texas [Member]
Disaggregation of Revenue [Line Items]
Revenues	[1]	140	608
East [Member]
Disaggregation of Revenue [Line Items]
Revenues	[1]	614	416
Retail [Member]
Disaggregation of Revenue [Line Items]
Revenues	[1]	938	$ 960
Energy and Other Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		1,078
Energy and Other Products [Member] | West [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		199
Energy and Other Products [Member] | Texas [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		304
Energy and Other Products [Member] | East [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		132
Energy and Other Products [Member] | Retail [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		443
Energy and Other Products [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0
Capacity Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		194
Capacity Revenue [Member] | West [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		19
Capacity Revenue [Member] | Texas [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		26
Capacity Revenue [Member] | East [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		149
Capacity Revenue [Member] | Retail [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0
Capacity Revenue [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0
Revenues Relating to Physical or Executory Contracts - Third Party [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		1,272
Revenues Relating to Physical or Executory Contracts - Third Party [Member] | West [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		218
Revenues Relating to Physical or Executory Contracts - Third Party [Member] | Texas [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		330
Revenues Relating to Physical or Executory Contracts - Third Party [Member] | East [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		281
Revenues Relating to Physical or Executory Contracts - Third Party [Member] | Retail [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		443
Revenues Relating to Physical or Executory Contracts - Third Party [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0
Affiliate Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	0
Affiliate Revenue [Member] | West [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	8
Affiliate Revenue [Member] | Texas [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	4
Affiliate Revenue [Member] | East [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	21
Affiliate Revenue [Member] | Retail [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	1
Affiliate Revenue [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	(34)
Revenues Relating to Leases and Derivative Instruments [Member]
Disaggregation of Revenue [Line Items]
Revenues	[3]	$ 737

[1] Includes intersegment revenues of $114 million and $61 million in the West, $(67) million and $72 million in Texas, $115 million and $88 million in the East and $1 million and $1 million in Retail for the three months ended March 31, 2018 and 2017, respectively. Intersegment revenues for sales between wholesale and retail operations are executed to manage supply needs for our retail operations from our wholesale fleet or to facilitate margin collateral netting at Calpine Corporation.

[2] 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 Corporation.

[3] 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. For revenue related to derivative instruments, includes revenue recorded in Commodity revenue and mark-to-market gain (loss) on our Consolidated Condensed Statement of Operations.