Acquisition (Notes)	6 Months Ended
Jun. 30, 2015
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	Acquisitions Acquisition of Champion Energy On July 20, 2015, we announced that we have entered into an agreement, through our indirect, wholly-owned subsidiary Calpine Energy Services Holdco LLC, to purchase Champion Energy Marketing, LLC from Champion Energy Holdings, LLC, which owns a 75% interest, and EDF Trading North America, LLC, which owns a 25% interest, for approximately $240 million, excluding working capital adjustments. Champion Energy, a leading retail electric provider, is expected to serve approximately 22 million MWh of commercial, industrial and residential customer load in 2015, concentrated in Texas, PJM and the Northeast U.S. where Calpine has a substantial power generation presence. The addition of this well-established retail sales organization is expected to provide us an important outlet for directly reaching a much greater portion of the load we serve. We expect the transaction to close by the fourth quarter of 2015, subject to regulatory approvals, and will fund the acquisition with cash on hand. Acquisition of Fore River Energy Center On November 7, 2014, we, through our indirect, wholly-owned subsidiary Calpine Fore River Energy Center, LLC, completed the purchase of Fore River Energy Center, a power plant with a nameplate capacity of 809 MW, and related plant inventory from a subsidiary of Exelon Corporation, for approximately $530 million, excluding working capital adjustments. During the six months ended June 30, 2015, there were no material adjustments made to the initial purchase price allocation recorded in the fourth quarter of 2014 related to our acquisition of Fore River Energy Center. Although the purchase price allocation has not been finalized, we do not expect to record any material adjustments to the preliminary purchase price allocation nor do we expect to recognize any goodwill as a result of this acquisition.

Acquisitions

Acquisition of Champion Energy

On July 20, 2015, we announced that we have entered into an agreement, through our indirect, wholly-owned subsidiary Calpine Energy Services Holdco LLC, to purchase Champion Energy Marketing, LLC from Champion Energy Holdings, LLC, which owns a 75% interest, and EDF Trading North America, LLC, which owns a 25% interest, for approximately $240 million, excluding working capital adjustments. Champion Energy, a leading retail electric provider, is expected to serve approximately 22 million MWh of commercial, industrial and residential customer load in 2015, concentrated in Texas, PJM and the Northeast U.S. where Calpine has a substantial power generation presence. The addition of this well-established retail sales organization is expected to provide us an important outlet for directly reaching a much greater portion of the load we serve. We expect the transaction to close by the fourth quarter of 2015, subject to regulatory approvals, and will fund the acquisition with cash on hand.

Acquisition of Fore River Energy Center

On November 7, 2014, we, through our indirect, wholly-owned subsidiary Calpine Fore River Energy Center, LLC, completed the purchase of Fore River Energy Center, a power plant with a nameplate capacity of 809 MW, and related plant inventory from a subsidiary of Exelon Corporation, for approximately $530 million, excluding working capital adjustments. During the six months ended June 30, 2015, there were no material adjustments made to the initial purchase price allocation recorded in the fourth quarter of 2014 related to our acquisition of Fore River Energy Center. Although the purchase price allocation has not been finalized, we do not expect to record any material adjustments to the preliminary purchase price allocation nor do we expect to recognize any goodwill as a result of this acquisition.