Derivative Instruments (Details 5) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		$ 55	$ (4)
Depreciation expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	[1],[2]	1	0
Interest Rate Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	[1],[2]	54	(4)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	[3]	(7)	(11)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Depreciation expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	[1],[2],[3]	(1)	0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	[1],[2],[3]	$ (6)	$ (11)

[1] We did not record any material gain (loss) on hedge ineffectiveness related to our interest rate hedging instruments designated as cash flow hedges during the three months ended March 31, 2018 and 2017.

[2] We recorded an income tax expense of $11 million and nil for the three months ended March 31, 2018 and 2017, respectively, in AOCI related to our cash flow hedging activities.

[3] Cumulative cash flow hedge losses attributable to Calpine, net of tax, remaining in AOCI were $30 million and $72 million at March 31, 2018 and December 31, 2017, respectively. Cumulative cash flow hedge losses attributable to the noncontrolling interest, net of tax, remaining in AOCI were $4 million and $6 million at March 31, 2018 and December 31, 2017, respectively.