Derivative Instruments (Details 5) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment for loss on cash flow hedges realized in net income (loss)		$ (25)	$ 3	$ (31)	$ 5
Interest rate hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax	[1]	3	(32)	(101)	(57)
Reclassification adjustment for loss on cash flow hedges realized in net income (loss)	[1],[2],[3]	$ (25)	$ 3	$ (31)	$ 5

[1] We recorded an income tax expense of $1 million and an income tax (benefit) of $(1) million for the three months ended June 30, 2020 and 2019, respectively, and income tax (benefit) of $(2) million and $(1) million for the six months ended June 30, 2020 and 2019, respectively, in AOCI related to our cash flow hedging activities.

[2] Cumulative cash flow hedge losses attributable to Calpine, net of tax, remaining in AOCI were $174 million and $72 million at June 30, 2020 and December 31, 2019, respectively. Cumulative cash flow hedge losses attributable to the noncontrolling interest, net of tax, remaining in AOCI were nil and $3 million at June 30, 2020 and December 31, 2019, respectively.

[3] Includes losses of $16 million and nil that were reclassified from AOCI to interest expense for the three months ended June 30, 2020 and 2019, respectively, and losses of $16 million and $1 million that were reclassified from AOCI to interest expense for the six months ended June 30, 2020 and 2019, respectively,where the hedged transactions became probable of not occurring.