Derivative Instruments (Details 4) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on cash flow hedges before reclassification adjustment for cash flow hedges realized in net income (loss)		$ (6)	$ (48)	$ (43)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax		46	26	41
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax	[1],[2]	45	21	41
Depreciation expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax	[1],[2]	1	5	0
Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on cash flow hedges before reclassification adjustment for cash flow hedges realized in net income (loss)		(6)	(48)	(43)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on cash flow hedges before reclassification adjustment for cash flow hedges realized in net income (loss)	[1],[2],[3],[4]	(5)	(43)	(43)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Depreciation expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on cash flow hedges before reclassification adjustment for cash flow hedges realized in net income (loss)	[1],[2],[3],[4]	$ (1)	$ (5)	$ 0

[1] We recorded a gain of $1 million on hedge ineffectiveness related to our interest rate hedging instruments designated as cash flow hedges during the years ended December 31, 2018 and 2017. 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 year ended December 31, 2016.

[2] We recorded income tax expense of $5 million, $6 million and $1 million for the years ended December 31, 2018, 2017 and 2016, 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 $34 million, $72 million and $90 million at December 31, 2018, 2017 and 2016, respectively. Cumulative cash flow hedge losses attributable to the noncontrolling interest, net of tax, remaining in AOCI were $3 million, $6 million and $8 million at December 31, 2018, 2017 and 2016, respectively.

[4] Includes losses of $1 million, nil and $3 million that were reclassified from AOCI to interest expense for the years ended December 31, 2018, 2017 and 2016, respectively, where the hedged transactions became probable of not occurring.