Divestitures (Notes)	3 Months Ended
Mar. 31, 2019
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	Sale of Garrison Energy Center and RockGen Energy Center On April 8, 2019, we, through our indirect, wholly-owned subsidiaries Calpine Holdings, LLC and Calpine Northbrook Project Holdings, LLC, entered into an agreement with Cobalt Power, L.L.C. to sell 100% of our ownership interests in Garrison Energy Center LLC (“Garrison”) and RockGen Energy LLC (“RockGen”) for approximately $360 million, subject to certain working capital adjustments and the execution of contracts. Garrison is an indirect, wholly-owned subsidiary that owns the Garrison Energy Center, a 309 MW natural gas-fired, combined-cycle power plant located in Dover, Delaware and RockGen is an indirect, wholly-owned subsidiary that owns the RockGen Energy Center, a 503 MW natural gas-fired, simple-cycle power plant located in Christiana, Wisconsin. We expect the sale, which is subject to regulatory approvals, to close in the third quarter of 2019 and we will use the sale proceeds for our capital allocation activities and general corporate purposes. At March 31, 2019, we have reclassified the assets and liabilities of Garrison Energy Center and RockGen Energy Center, which are part of our East segment, to current assets and liabilities held for sale on our Consolidated Condensed Balance Sheet consisting primarily of property, plant and equipment, net, and finance leases, respectively, and recorded an immaterial adjustment to the carrying value to reflect fair value less cost to sell.

Sale of Garrison Energy Center and RockGen Energy Center

On April 8, 2019, we, through our indirect, wholly-owned subsidiaries Calpine Holdings, LLC and Calpine Northbrook Project Holdings, LLC, entered into an agreement with Cobalt Power, L.L.C. to sell 100% of our ownership interests in Garrison Energy Center LLC (“Garrison”) and RockGen Energy LLC (“RockGen”) for approximately $360 million, subject to certain working capital adjustments and the execution of contracts. Garrison is an indirect, wholly-owned subsidiary that owns the Garrison Energy Center, a 309 MW natural gas-fired, combined-cycle power plant located in Dover, Delaware and RockGen is an indirect, wholly-owned subsidiary that owns the RockGen Energy Center, a 503 MW natural gas-fired, simple-cycle power plant located in Christiana, Wisconsin. We expect the sale, which is subject to regulatory approvals, to close in the third quarter of 2019 and we will use the sale proceeds for our capital allocation activities and general corporate purposes.

At March 31, 2019, we have reclassified the assets and liabilities of Garrison Energy Center and RockGen Energy Center, which are part of our East segment, to current assets and liabilities held for sale on our Consolidated Condensed Balance Sheet consisting primarily of property, plant and equipment, net, and finance leases, respectively, and recorded an immaterial adjustment to the carrying value to reflect fair value less cost to sell.