Derivative Instruments (Details 5) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense		$ 158	$ 159	$ 472	$ 471
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]	18	(4)	0	4
Interest expense	[3]	0	1	1	2
Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense	[1],[2],[4],[5]	$ (11)	$ (12)	$ (33)	$ (36)

[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 and nine months ended September 30, 2016 and 2015.

[2] We recorded an income tax expense of nil for each of the three and nine months ended September 30, 2016 and 2015, in AOCI related to our cash flow hedging activities.

[3] In addition to changes in market value on derivatives not designated as hedges, changes in mark-to-market gain (loss) also includes de-designation of interest rate swap cash flow hedges and related reclassification of AOCI into earnings, hedge ineffectiveness and adjustments to reflect changes in credit default risk exposure.

[4] Cumulative cash flow hedge losses attributable to Calpine, net of tax, remaining in AOCI were $127 million and $127 million at September 30, 2016 and December 31, 2015, respectively. Cumulative cash flow hedge losses attributable to the noncontrolling interest, net of tax, remaining in AOCI were $11 million and $11 million at September 30, 2016 and December 31, 2015, respectively.

[5] Includes a loss of $1 million for each of the three and nine months ended September 30, 2016, that was reclassified from AOCI to interest expense, where the hedged transactions are no longer expected to occur.