Commitments and Contingencies (Schedule of Guarantor Obligations) (Details) $ in Millions	Dec. 31, 2018 USD ($)
Loans Payable [Member]
Guarantor Obligations [Line Items]
Guarantee Obligations Balance On First Anniversary	$ 30	[1]
Guarantee Obligations Balance On Second Anniversary	30	[1]
Guarantee Obligations Balance On Third Anniversary	29	[1]
Guarantee Obligations Balance On Fourth Anniversary	24	[1]
Guarantee Obligations Balance On Fifth Anniversary	14	[1]
Guarantee Obligations Due After Five Years	52	[1]
Guarantor Obligations, Maximum Exposure, Undiscounted	179	[1]
Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Guarantee Obligations Balance On First Anniversary	1,321	[2],[3],[4]
Guarantee Obligations Balance On Second Anniversary	6	[2],[3],[4]
Guarantee Obligations Balance On Third Anniversary	0	[2],[3],[4]
Guarantee Obligations Balance On Fourth Anniversary	0	[2],[3],[4]
Guarantee Obligations Balance On Fifth Anniversary	38	[2],[3],[4]
Guarantee Obligations Due After Five Years	0	[2],[3],[4]
Guarantor Obligations, Maximum Exposure, Undiscounted	1,365	[2],[3],[4]
Surety Bonds [Member]
Guarantor Obligations [Line Items]
Guarantee Obligations Balance On First Anniversary	12	[4],[5],[6]
Guarantee Obligations Balance On Second Anniversary	7	[4],[5],[6]
Guarantee Obligations Balance On Third Anniversary	0	[4],[5],[6]
Guarantee Obligations Balance On Fourth Anniversary	0	[4],[5],[6]
Guarantee Obligations Balance On Fifth Anniversary	0	[4],[5],[6]
Guarantee Obligations Due After Five Years	76	[4],[5],[6]
Guarantor Obligations, Maximum Exposure, Undiscounted	95	[4],[5],[6]
Accounts Receivable Sales Program [Member]
Guarantor Obligations [Line Items]
Guarantee Obligations Balance On First Anniversary	238	[7]
Guarantee Obligations Balance On Second Anniversary	0	[7]
Guarantee Obligations Balance On Third Anniversary	0	[7]
Guarantee Obligations Balance On Fourth Anniversary	0	[7]
Guarantee Obligations Balance On Fifth Anniversary	0	[7]
Guarantee Obligations Due After Five Years	0	[7]
Guarantor Obligations, Maximum Exposure, Undiscounted	238	[7]
Gurantee Obligations Total [Member]
Guarantor Obligations [Line Items]
Guarantee Obligations Balance On First Anniversary	1,601
Guarantee Obligations Balance On Second Anniversary	43
Guarantee Obligations Balance On Third Anniversary	29
Guarantee Obligations Balance On Fourth Anniversary	24
Guarantee Obligations Balance On Fifth Anniversary	52
Guarantee Obligations Due After Five Years	128
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 1,877

[1] Represents Calpine Corporation guarantees of certain power plant capital leases and related interest. All guaranteed capital leases are recorded on our Consolidated Balance Sheets.

[2] Letters of credit are renewed annually and as such all amounts are reflected in the year of letter of credit expiration. The related commercial obligations extend for multiple years, therefore, renewal of the letter of credit will likely follow the term of the associated commercial obligation.

[3] The standby letters of credit disclosed above represent those disclosed in Note 8.

[4] These are contingent off balance sheet obligations.

[5] As of December 31, 2018, no cash collateral is outstanding related to these bonds.

[6] The majority of surety bonds do not have expiration or cancellation dates.

[7] Calpine has guaranteed the performance of Calpine Solutions under the Accounts Receivable Sales Program. The Accounts Receivable Sales Program expires on November 29, 2019.