Quarterly Consolidated Financial Data (unaudited) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Operating revenues	$ 2,354	$ 2,890	$ 2,259	$ 2,009	$ 1,801	$ 2,586	$ 2,084	$ 2,281	$ 9,512	[1]	$ 8,752	[1]	$ 6,716	[1]
Income (loss) from operations	105	568	417	(328)	(100)	393	13	72	762		378		839
Net income (loss) attributable to Calpine	$ (16)	$ 272	$ 352	$ (598)	$ (292)	$ 225	$ (216)	$ (56)	$ 10		$ (339)		$ 92

[1] Includes intersegment revenues of $488 million, $324 million and $20 million in the West, $573 million, $361 million and $81 million in Texas, $234 million, $237 million and $48 million in the East and $4 million, $4 million, $2 million in Retail for the years ended December 31, 2018, 2017 and 2016, respectively.