Calpine (CPNLQ) 10-Q 8 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Aug. 07, 2019
Entity Information [Line Items]
Entity Registrant Name	CALPINE CORP
Entity Central Index Key	0000916457
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Current Reporting Status	No
Entity Common Stock, Shares Outstanding		105.2

Consolidated Condensed Statemen

Consolidated Condensed Statements of Operations - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019		Jun. 30, 2018		Jun. 30, 2019		Jun. 30, 2018
Operating revenues:
Commodity revenue	$ 2,128		$ 2,121		$ 4,666		$ 4,517
Mark-to-market gain (loss)	467		131		523		(260)
Other revenue	4		7		9		11
Operating revenues	2,599	[1]	2,259	[1]	5,198	[2]	4,268	[2]
Operating expenses:
Commodity expense	1,367		1,426		3,125		3,216
Mark-to-market (gain) loss	280		(57)		290		(77)
Fuel and purchased energy expense	1,647		1,369		3,415		3,139
Operating and maintenance expense	245		242		484		517
Depreciation and amortization expense	175		186		349		387
General and other administrative expense	34		31		66		91
Other operating expenses	19		19		38		56
Total operating expenses	2,120		1,847		4,352		4,190
Impairment losses	40		0		55		0
(Income) from unconsolidated subsidiaries	(5)		(5)		(11)		(11)
Income from operations	444		417		802		89
Interest expense	157		157		306		308
(Gain) loss on extinguishment of debt	3		0		(1)		0
Other (income) expense, net	5		62		28		69
Income (loss) before income taxes	279		198		469		(288)
Income tax expense (benefit)	9		(158)		19		(50)
Net income (loss)	270		356		450		(238)
Net income attributable to the noncontrolling interest	(4)		(4)		(9)		(8)
Net income (loss) attributable to Calpine	$ 266		$ 352		$ 441		$ (246)
[1]	Includes intersegment revenues of $100 million and $70 million in the West, $348 million and $276 million in Texas, $228 million and $18 million in the East and $1 million and $1 million in Retail for the three months ended June 30, 2019 and 2018, respectively.
[2]	Includes intersegment revenues of $262 million and $184 million in the West, $559 million and $209 million in Texas, $365 million and $133 million in the East and $4 million and $2 million in Retail for the six months ended June 30, 2019 and 2018, respectively.

Consolidated Condensed Statem_2

Consolidated Condensed Statements of Comprehensive Income - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 270	$ 356	$ 450	$ (238)
Cash flow hedging activities:
Gain (loss) on cash flow hedges before reclassification adjustment for cash flow hedges realized in net income (loss)		(29)	15	(52)	63
Reclassification adjustment for (gain) loss on cash flow hedges realized in net income (loss)	[1],[2]	(3)	0	(5)	7
Foreign currency translation gain (loss)		1	(2)	3	(8)
Income tax benefit (expense)		1	7	1	(4)
Other comprehensive income (loss)		(30)	20	(53)	58
Comprehensive income (loss)		240	376	397	(180)
Comprehensive (income) attributable to the noncontrolling interest		(3)	(4)	(8)	(10)
Comprehensive income (loss) attributable to Calpine		$ 237	$ 372	$ 389	$ (190)
[1]	Cumulative cash flow hedge losses attributable to Calpine, net of tax, remaining in AOCI were $89 million and $34 million at June 30, 2019 and December 31, 2018, respectively. Cumulative cash flow hedge losses attributable to the noncontrolling interest, net of tax, remaining in AOCI were $4 million and $3 million at June 30, 2019 and December 31, 2018, respectively.
[2]	Includes losses (gains) of nil that were reclassified from AOCI to interest expense for the three months ended June 30, 2019 and 2018, and losses of $1 million and nil that were reclassified from AOCI to interest expense for the six months ended June 30, 2019 and 2018, respectively, where the hedged transactions became probable of not occurring.

Consolidated Condensed Balance

Consolidated Condensed Balance Sheets - USD ($) $ in Millions		Jun. 30, 2019		Dec. 31, 2018
Current assets:
Cash and cash equivalents ($33 and $43 attributable to VIEs)		$ 297		$ 205
Accounts receivable, net of allowance of $8 and $9		806		1,022
Inventories		541		525
Margin deposits and other prepaid expense		276		315
Restricted cash, current ($108 and $90 attributable to VIEs)		182		167
Derivative assets, current	[1]	202	[2]	142	[3]
Current assets held for sale		335		0
Other current assets		60		43
Total current assets		2,699		2,419
Property, plant and equipment, net ($3,873 and $3,919 attributable to VIEs)		12,051		12,442
Restricted cash, net of current portion ($48 and $33 attributable to VIEs)		80		34
Investments in unconsolidated subsidiaries		71		76
Derivative Asset, Noncurrent	[1]	213	[2]	160	[3]
Goodwill		242		242
Intangible assets, net		370		412
Other assets ($100 and $30 attributable to VIEs)		483		277
Total assets		16,209		16,062
Current liabilities:
Accounts payable		695		958
Accrued interest payable		98		96
Debt, current portion ($213 and $201 attributable to VIEs)		263		637
Derivative Liability, Current	[1]	165	[2]	303	[3]
Current liabilitites held for sale		22		0
Other current liabilities ($71 and $36 attributable to VIEs)		470		489
Total current liabilities		1,713		2,483
Debt, net of current portion ($1,889 and $1,978 attributable to VIEs)		10,461		10,148
Long-term derivative liabilities	[1]	119	[2]	140	[3]
Other long-term liabilities ($73 and $36 attributable to VIEs)		463		235
Total liabilities		12,756		13,006
Commitments and contingencies (see Note 11)
Stockholder’s equity:
Common stock, $0.001 par value per share; authorized 5,000 shares, 105.2 shares issued and outstanding		0		0
Additional paid-in capital		9,584		9,582
Accumulated deficit		(6,101)		(6,542)
Accumulated other comprehensive loss		(129)		(77)
Total Calpine stockholder’s equity		3,354		2,963
Noncontrolling interest		99		93
Total stockholder’s equity		3,453		3,056
Total liabilities and stockholder’s equity		$ 16,209		$ 16,062
[1]	At June 30, 2019 and December 31, 2018, we had $142 million and $244 million, respectively, of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets primarily related to initial margin requirements.
[2]	At June 30, 2019, current and long-term derivative assets are shown net of collateral of $(27) million and $(3) million, respectively, and current and long-term derivative liabilities are shown net of collateral of $72 million and $104 million, respectively.
[3]	At December 31, 2018, current and long-term derivative assets are shown net of collateral of $(58) million and $(8) million, respectively, and current and long-term derivative liabilities are shown net of collateral of $49 million and $64 million, respectively.

Consolidated Condensed Balanc_2

Consolidated Condensed Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Cash and cash equivalents ($33 and $43 attributable to VIEs)	$ 297	$ 205
Accounts receivable, net of allowance of $8 and $9	8	9
Restricted cash, current ($108 and $90 attributable to VIEs)	182	167
Property, plant and equipment, net ($3,873 and $3,919 attributable to VIEs)	12,051	12,442
Restricted cash, net of current portion ($48 and $33 attributable to VIEs)	80	34
Other assets ($100 and $30 attributable to VIEs)	483	277
Debt, current portion ($213 and $201 attributable to VIEs)	263	637
Other current liabilities ($71 and $36 attributable to VIEs)	470	489
Debt, net of current portion ($1,889 and $1,978 attributable to VIEs)	10,461	10,148
Other long-term liabilities ($73 and $36 attributable to VIEs)	$ 463	$ 235
Common Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Common Stock, Shares Authorized	5,000	5,000
Common Stock, Shares, Issued	105.2	105.2
Common Stock, Shares, Outstanding	105.2	105.2
Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents ($33 and $43 attributable to VIEs)	$ 33	$ 43
Restricted cash, current ($108 and $90 attributable to VIEs)	108	90
Property, plant and equipment, net ($3,873 and $3,919 attributable to VIEs)	3,873	3,919
Restricted cash, net of current portion ($48 and $33 attributable to VIEs)	48	33
Other assets ($100 and $30 attributable to VIEs)	100	30
Debt, current portion ($213 and $201 attributable to VIEs)	213	201
Other current liabilities ($71 and $36 attributable to VIEs)	71	36
Debt, net of current portion ($1,889 and $1,978 attributable to VIEs)	1,889	1,978
Other long-term liabilities ($73 and $36 attributable to VIEs)	$ 73	$ 36

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity Statement - USD ($) $ in Millions		Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]
Beginning Balance at Dec. 31, 2017		$ 3,067	$ 0	$ (15)	$ 9,661	$ (6,552)	$ (106)	$ 79
Treasury Stock, Value, Acquired, Cost Method		(7)	0	(7)	0	0	0	0
Stock-based compensation expense		41	0	0	41	0	0	0
Other		(78)	0	22	(100)	0	0	0
Dividends paid		(20)	0	0	(20)	0	0	0
Contribution from the noncontrolling interest		2	0	0	0	0	0	2
Distribution to the noncontrolling interest		(2)	0	0	0	0	0	(2)
Net income (loss)		(594)	0	0	0	(598)	0	4
Other comprehensive income (loss)		38	0	0	0	0	36	2
Ending Balance at Mar. 31, 2018		2,447	0	0	9,582	(7,150)	(70)	85
Beginning Balance at Dec. 31, 2017		3,067	0	(15)	9,661	(6,552)	(106)	79
Dividends paid	[1]	(18)
Distribution to the noncontrolling interest		(3)
Net income (loss)		(238)
Other comprehensive income (loss)		58
Ending Balance at Jun. 30, 2018		2,822	0	0	9,582	(6,798)	(50)	88
Beginning Balance at Mar. 31, 2018		2,447	0	0	9,582	(7,150)	(70)	85
Distribution to the noncontrolling interest		(1)	0	0	0	0	0	(1)
Net income (loss)		356	0	0	0	352	0	4
Other comprehensive income (loss)		20	0	0	0	0	20	0
Ending Balance at Jun. 30, 2018		2,822	0	0	9,582	(6,798)	(50)	88
Beginning Balance at Dec. 31, 2018		3,056	0	0	9,582	(6,542)	(77)	93
Other		0	0	0	2	0	0	(2)
Net income (loss)		180	0	0	0	175	0	5
Other comprehensive income (loss)		(23)	0	0	0	0	(23)	0
Ending Balance at Mar. 31, 2019		3,213	0	0	9,584	(6,367)	(100)	96
Beginning Balance at Dec. 31, 2018		3,056	0	0	9,582	(6,542)	(77)	93
Dividends paid	[1]	0
Distribution to the noncontrolling interest		0
Net income (loss)		450
Other comprehensive income (loss)		(53)
Ending Balance at Jun. 30, 2019		3,453	0	0	9,584	(6,101)	(129)	99
Beginning Balance at Mar. 31, 2019		3,213	0	0	9,584	(6,367)	(100)	96
Net income (loss)		270	0	0	0	266	0	4
Other comprehensive income (loss)		(30)	0	0	0	0	(29)	(1)
Ending Balance at Jun. 30, 2019		$ 3,453	$ 0	$ 0	$ 9,584	$ (6,101)	$ (129)	$ 99
[1]	Subsequent to the consummation of the Merger on March 8, 2018, we paid certain Merger-related costs incurred by CPN Management, our direct parent.

Consolidated Condensed Statem_3

Consolidated Condensed Statements of Cash Flows - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income (loss)		$ 450	$ (238)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization(1)	[1]	398	443
Deferred income taxes		16	36
Impairment losses		55	0
Mark-to-market activity, net	[2]	(231)	180
(Income) from unconsolidated subsidiaries		(11)	(11)
Return on investments from unconsolidated subsidiaries		11	5
Stock-based compensation expense		0	57
Other		(3)	9
Change in operating assets and liabilities:
Accounts receivable		215	(8)
Accounts payable		(269)	(11)
Margin deposits and other prepaid expense		40	(90)
Other assets and liabilities, net		(61)	(242)
Derivative instruments, net		(91)	(74)
Net cash provided by operating activities		519	56
Cash flows from investing activities:
Purchases of property, plant and equipment		(304)	(231)
Other		(11)	(3)
Net cash used in investing activities		(315)	(234)
Cash flows from financing activities:
Borrowings under First Lien Term Loans		941	0
Repayment of CCFC Term Loan and First Lien Term Loans		(942)	(21)
Repurchases of Senior Unsecured Notes		(44)	0
Borrowings under Corporate Revolving Facility		220	475
Repayments of Corporate Revolving Facility		(175)	(200)
Borrowings from project financing, notes payable and other		34	0
Repayments of project financing, notes payable and other		(77)	(66)
Distribution to noncontrolling interest holder		0	(3)
Financing costs		(8)	(12)
Stock repurchases		0	(79)
Shares repurchased for tax withholding on stock-based awards		0	(7)
Dividends paid(2)	[3]	0	(18)
Net cash (used in) provided by financing activities		(51)	69
Net increase (decrease) in cash, cash equivalents and restricted cash		153	(109)
Cash, cash equivalents and restricted cash, beginning of period		406	443
Cash, cash equivalents and restricted cash, end of period(3)	[4]	559	334
Cash paid during the period for:
Interest, net of amounts capitalized		283	284
Income taxes		8	10
Supplemental disclosure of non-cash investing and financing activities:
Change in capital expenditures included in account payable		19	(14)
Plant tax settlement offset in prepaid assets		(4)	0
Asset retirement obligation adjustment offset in operating activities		(10)	0
Current Assets Held for Sale [Member]
Supplemental disclosure of non-cash investing and financing activities:
Current assets (liabilities) held for sale		(335)	0
Current Liabilities Held for Sale [Member]
Supplemental disclosure of non-cash investing and financing activities:
Current assets (liabilities) held for sale		$ 22	$ 0
[1]	Includes amortization recorded in Commodity revenue and Commodity expense associated with intangible assets and amortization recorded in interest expense associated with debt issuance costs and discounts.
[2]	In addition to changes in market value on derivatives not designated as hedges, changes in mark-to-market gain (loss) also includes adjustments to reflect changes in credit default risk exposure.
[3]	Subsequent to the consummation of the Merger on March 8, 2018, we paid certain Merger-related costs incurred by CPN Management, our direct parent.
[4]	Our cash and cash equivalents, restricted cash, current and restricted cash, net of current portion are stated as separate line items on our Consolidated Condensed Balance Sheets.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Summary of significant accounting policies	Basis of Presentation and Summary of Significant Accounting Policies We are a power generation company engaged in the ownership and operation of primarily natural gas-fired and geothermal power plants in North America. We have a significant presence in major competitive wholesale and retail power markets in California, Texas and the Northeast and Mid-Atlantic regions of the U.S. We sell power, steam, capacity, renewable energy credits and ancillary services to our customers, which include utilities, independent electric system operators, industrial and agricultural companies, retail power providers, municipalities and other governmental entities, power marketers as well as retail commercial, industrial, governmental and residential customers. We continue to focus on providing products and services that are beneficial to our wholesale and retail customers. We purchase primarily natural gas and some fuel oil as fuel for our power plants and engage in related natural gas transportation and storage transactions. We also purchase power for sale to our customers and purchase electric transmission rights to deliver power to our customers. Additionally, consistent with our Risk Management Policy, we enter into natural gas, power, environmental product, fuel oil and other physical and financial commodity contracts to hedge certain business risks and optimize our portfolio of power plants. Basis of Interim Presentation — The accompanying unaudited, interim Consolidated Condensed Financial Statements of Calpine Corporation, a Delaware corporation, and consolidated subsidiaries have been prepared pursuant to the rules and regulations of the SEC. In the opinion of management, the Consolidated Condensed Financial Statements include the normal, recurring adjustments necessary for a fair statement of the information required to be set forth therein. Certain information and note disclosures, normally included in financial statements prepared in accordance with U.S. GAAP, have been condensed or omitted from these statements pursuant to such rules and regulations and, accordingly, these financial statements should be read in conjunction with our audited Consolidated Financial Statements for the year ended December 31, 2018 , included in our 2018 Form 10-K. The results for interim periods are not indicative of the results for the entire year primarily due to acquisitions and disposals of assets, seasonal fluctuations in our revenues and expenses, timing of major maintenance expense, variations resulting from the application of the method to calculate the provision for income tax for interim periods, volatility of commodity prices and mark-to-market gains and losses from commodity and interest rate derivative contracts. Use of Estimates in Preparation of Financial Statements — The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures included in our Consolidated Condensed Financial Statements. Actual results could differ from those estimates. Reclassifications — We have reclassified certain prior period amounts for comparative purposes. These reclassifications did not have a material effect on our financial condition, results of operations or cash flows. Cash and Cash Equivalents — We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents. We have cash and cash equivalents held in non-corporate accounts relating to certain project finance facilities and lease agreements that require us to establish and maintain segregated cash accounts. These accounts have been pledged as security in favor of the lenders under such project finance facilities, and the use of certain cash balances on deposit in such accounts is limited, at least temporarily, to the operations of the respective projects. Restricted Cash — Certain of our debt agreements, lease agreements or other operating agreements require us to establish and maintain segregated cash accounts, the use of which is restricted, making these cash funds unavailable for general use. These amounts are held by depository banks in order to comply with the contractual provisions requiring reserves for payments such as for debt service, rent and major maintenance or with applicable regulatory requirements. Funds that can be used to satisfy obligations due during the next 12 months are classified as current restricted cash, with the remainder classified as non-current restricted cash. Restricted cash is generally invested in accounts earning market rates; therefore, the carrying value approximates fair value. Such cash is excluded from cash and cash equivalents on our Consolidated Condensed Balance Sheets. The table below represents the components of our restricted cash as of June 30, 2019 and December 31, 2018 (in millions): June 30, 2019 December 31, 2018 Current Non-Current Total Current Non-Current Total Debt service $ 51 $ 8 $ 59 $ 13 $ 8 $ 21 Construction/major maintenance 9 39 48 23 24 47 Security/project/insurance 112 31 143 120 — 120 Other 10 2 12 11 2 13 Total $ 182 $ 80 $ 262 $ 167 $ 34 $ 201 Business Interruption Proceeds — We record business interruption insurance proceeds in operating revenues when they are realizable. We recorded approximately $14 million of business interruption proceeds for each of the three and six months ended June 30, 2018 . We have not recorded any business interruption insurance proceeds during the three and six months ended June 30, 2019 . Property, Plant and Equipment, Net — At June 30, 2019 and December 31, 2018 , the components of property, plant and equipment are stated at cost less accumulated depreciation as follows (in millions): June 30, 2019 December 31, 2018 Depreciable Lives Buildings, machinery and equipment $ 16,522 $ 16,400 1.5 – 50 Years Geothermal properties 1,509 1,501 13 – 58 Years Other 269 286 3 – 50 Years 18,300 18,187 Less: Accumulated depreciation 6,860 6,832 11,440 11,355 Land 128 121 Construction in progress 483 966 Property, plant and equipment, net $ 12,051 $ 12,442 Capitalized Interest — The total amount of interest capitalized was $1 million and $7 million during the three months ended June 30, 2019 and 2018 , respectively, and $8 million and $14 million during the six months ended June 30, 2019 and 2018 , respectively. Goodwill — We have not recorded any impairment losses or changes in the carrying amount of our goodwill during the three and six months ended June 30, 2019 and 2018 . New Accounting Standards and Disclosure Requirements Leases — On January 1, 2019, we adopted Accounting Standards Update 2016-02, “Leases” (“Topic 842”). The comprehensive new lease standard superseded all existing lease guidance. The standard requires that a lessee should recognize a right-of-use asset and a lease liability for substantially all operating leases based on the present value of the minimum rental payments. For lessors, the accounting for leases under Topic 842 remained substantially unchanged. The standard also requires expanded disclosures surrounding leases. We adopted the standards under Topic 842 using the modified retrospective method and elected a number of the practical expedients in our implementation of Topic 842. The key change that affected us relates to our accounting for operating leases for which we are the lessee that were historically off-balance sheet. The impact of adopting the standards resulted in the recognition of a right-of-use asset and lease obligation liability of $191 million on our Consolidated Condensed Balance Sheet on January 1, 2019, exclusive of previously recognized lease balances. The implementation of Topic 842 did not have a material effect on our Consolidated Condensed Statement of Operations or Consolidated Condensed Statement of Cash Flows for the six months ended June 30, 2019 . See Note 3 for a discussion of the practical expedients we elected and additional disclosures required by Topic 842. Derivatives and Hedging — In August 2017, the FASB issued Accounting Standards Update 2017-12, “Targeted Improvements to Accounting for Hedging Activities.” The standard better aligns an entity’s hedging activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results in the financial statements. The standard will prospectively make hedge accounting easier to apply to hedging activities and also enhances disclosure requirements for how hedge transactions are reflected in the financial statements when hedge accounting is elected. We adopted Accounting Standards Update 2017-12 in the first quarter of 2019 which did not have a material effect on our financial condition, results of operations or cash flows. Fair Value Measurements — In August 2018, the FASB issued Accounting Standards Update 2018-13, “Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement.” The standard removes, modifies and adds disclosures about fair value measurements and is effective for fiscal years beginning after December 15, 2019. The changes required by this standard to remove or modify disclosures may be early adopted with adoption of the additional disclosures required by this standard delayed until their effective date. We do not anticipate a material effect on our financial condition, results of operations or cash flows as a result of adopting this standard.

Revenue From Contracts with Cus

Revenue From Contracts with Customers (Notes)	6 Months Ended
	Jun. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	Revenue from Contracts with Customers Disaggregation of Revenues with Customers The following tables represent a disaggregation of our revenue for the three and six months ended June 30, 2019 and 2018 by reportable segment (in millions). See Note 13 for a description of our segments. Three Months Ended June 30, 2019 Wholesale West Texas East Retail Elimination Total Third-Party: Energy & other products $ 145 $ 318 $ 124 $ 413 $ — $ 1,000 Capacity 36 33 154 — — 223 Revenues relating to physical or executory contracts – third-party $ 181 $ 351 $ 278 $ 413 $ — $ 1,223 Affiliate (1) : $ 6 $ 14 $ 30 $ 1 $ (51 ) $ — Revenues relating to leases and derivative instruments (2) $ 1,376 Total operating revenues $ 2,599 Three Months Ended June 30, 2018 Wholesale West Texas East Retail Elimination Total Third-Party: Energy & other products $ 176 $ 326 $ 120 $ 451 $ — $ 1,073 Capacity 35 23 140 — — 198 Revenues relating to physical or executory contracts – third-party $ 211 $ 349 $ 260 $ 451 $ — $ 1,271 Affiliate (1) : $ 5 $ 9 $ 21 $ 1 $ (36 ) $ — Revenues relating to leases and derivative instruments (2) $ 988 Total operating revenues $ 2,259 Six Months Ended June 30, 2019 Wholesale West Texas East Retail Elimination Total Third-Party: Energy & other products $ 437 $ 620 $ 327 $ 825 $ — $ 2,209 Capacity 71 65 331 — — 467 Revenues relating to physical or executory contracts – third-party $ 508 $ 685 $ 658 $ 825 $ — $ 2,676 Affiliate (1) : $ 17 $ 28 $ 57 $ 4 $ (106 ) $ — Revenues relating to leases and derivative instruments (2) $ 2,522 Total operating revenues $ 5,198 Six Months Ended June 30, 2018 Wholesale West Texas East Retail Elimination Total Third-Party: Energy & other products $ 375 $ 630 $ 252 $ 894 $ — $ 2,151 Capacity 54 49 289 — — 392 Revenues relating to physical or executory contracts – third-party $ 429 $ 679 $ 541 $ 894 $ — $ 2,543 Affiliate (1) : $ 13 $ 13 $ 42 $ 2 $ (70 ) $ — Revenues relating to leases and derivative instruments (2) $ 1,725 Total operating revenues $ 4,268 ___________ (1) Affiliate energy, other and capacity revenues reflect revenues on transactions between wholesale and retail affiliates excluding affiliate activity related to leases and derivative instruments. All such activity supports retail supply needs from the wholesale business and/or allows for collateral margin netting efficiencies at Calpine. (2) Revenues relating to contracts accounted for as leases and derivatives include energy and capacity revenues relating to PPAs that we are required to account for as operating leases and physical and financial commodity derivative contracts, primarily relating to power, natural gas and environmental products. Revenue related to derivative instruments includes revenue recorded in Commodity revenue and mark-to-market gain (loss) within our operating revenues on our Consolidated Condensed Statements of Operations. Performance Obligations and Contract Balances At June 30, 2019 and December 31, 2018 , deferred revenue balances relating to contracts with our customers were included in other current liabilities on our Consolidated Condensed Balance Sheets and primarily relate to sales of environmental products and capacity. We classify deferred revenue as current or long-term based on the timing of when we expect to recognize revenue. The balance outstanding at June 30, 2019 and December 31, 2018 was $22 million and $14 million , respectively. Revenue recognized during the three months ended June 30, 2019 and 2018, relating to the deferred revenue balance at the beginning of each period was $2 million and $3 million , respectively. Revenue recognized during the six months ended June 30, 2019 and 2018, relating to the deferred revenue balance at the beginning of each period was and $3 million and $9 million , respectively. Revenue recognized each period relating to deferred revenue balances resulted from our performance under the customer contracts. The change in the deferred revenue balance during the three and six months ended June 30, 2019 and 2018 was primarily due to the timing difference of when consideration was received and when the related good or service was transferred. Performance Obligations not yet Satisfied As of June 30, 2019 , we have entered into certain contracts for fixed and determinable amounts with customers under which we have not yet completed our performance obligations which primarily includes agreements for which we are providing capacity from our generating facilities. We have revenues related to the sale of capacity through participation in various ISO capacity auctions estimated based upon cleared volumes and the sale of capacity to our customers of $258 million that will be recognized during the remainder of 2019, and $517 million , $468 million , $249 million and $50 million that will be recognized during the years ending December 31, 2020, 2021, 2022 and 2023, respectively, and $72 million thereafter. Revenues under these contracts will be recognized as we transfer control of the commodities to our customers.

Leases (Notes)

Leases (Notes)	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
LesseeandLessorLeases [Text Block]	Leases Accounting for Leases – Lessee We evaluate contracts for lease accounting at contract inception and assess lease classification at the lease commencement date. For our leases, we recognize a right-of-use asset and corresponding lease obligation liability at the lease commencement date where the lease obligation liability is measured at the present value of the minimum lease payments. For our operating leases, the amortization of the right-of-use asset and the accretion of our lease obligation liability result in a single straight-line expense recognized over the lease term. We determine the discount rate associated with our operating and finance leases using our incremental borrowing rate at lease commencement. For our operating leases, we use an interest rate commensurate with the interest rate to borrow on a collateralized basis over a similar term with an amount equal to the lease payments. Factors management considers in the calculation of the discount rate include the amount of the borrowing, the lease term including options that are reasonably certain of exercise, the current interest rate environment and the credit rating of the entity. For our finance leases, we use the interest rate commensurate with the interest rate for a project finance borrowing arrangement with a similar collateral package, repayment terms, restrictive covenants and guarantees. Our operating leases are primarily related to office space for our corporate and regional offices as well as land and operating related leases for our power plants. Additionally, one of our power plants is accounted for as a long-term operating lease. Payments made by Calpine on this lease are recognized on a straight-line basis with capital improvements associated with our leased power plant deemed leasehold improvements that are amortized over the shorter of the term of the lease or the economic life of the capital improvement. Several of our leases contain renewal options held by us to extend the lease term. The inclusion of these renewal periods in the lease term and in the minimum lease payments included in our lease liabilities is dependent on specific facts and circumstances for each lease and whether it is determined to be reasonably certain that we will exercise our option to extend the term. Our office, land and other operating leases do not contain any material restrictive covenants or residual value guarantees. We have entered into finance leases for certain power plants and related equipment with terms that range up to 30 years (including lease renewal options). The finance leases generally provide for the lessee to pay taxes, maintenance, insurance, and certain other operating costs of the leased property. In connection with our adoption of Topic 842 on January 1, 2019, we elected certain practical expedients that were available under the new lease standards including: • we elected not to separate lease and nonlease components for our current classes of underlying leased assets as the lessee; • we did not evaluate existing and expired land easements that were not previously accounted for as leases prior to January 1, 2019; and • we did not reassess the classification of leases, the accounting for initial direct costs or whether contractual arrangements contained a lease for all contracts that expired or commenced prior to January 1, 2019. Further, upon the adoption of Topic 842, we made an accounting policy election to not recognize lease assets and liabilities for leases with a term of 12 months or less. We do not have any material subleases associated with our operating and finance leases. The components of our operating and finance lease expense are as follows for the three and six months ended June 30, 2019 (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2019 Operating Leases Operating lease expense $ 12 $ 23 Finance Leases Amortization of the right-of-use assets $ 1 $ 4 Interest expense 2 4 Finance lease expense $ 3 $ 8 Variable lease expense $ 4 $ 5 Total lease expense $ 19 $ 36 The following is a schedule by year of future minimum lease payments associated with our operating and finance leases together with the present value of the net minimum lease payments as of June 30, 2019 (in millions): Operating Leases (1)(2) Finance Leases (2)(3) 2019 $ 39 $ 8 2020 20 16 2021 21 16 2022 19 16 2023 18 19 Thereafter 201 33 Total minimum lease payments 318 108 Less: Amount representing interest 108 30 Total lease obligation 210 78 Less: current lease obligation 39 10 Long-term lease obligation $ 171 $ 68 ____________ (1) The lease liabilities associated with our operating leases as of June 30, 2019 are included in other current liabilities and other long-term liabilities on our Consolidated Condensed Balance Sheet. (2) Excludes an operating lease obligation of $1 million and a finance lease obligation of $18 million related to Garrison Energy Center which are included in current liabilities held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center. (3) The lease liabilities associated with our finance leases as of June 30, 2019 are included in debt, current portion and debt, net of current portion on our Consolidated Condensed Balance Sheet. Supplemental balance sheet information related to our operating and finance leases is as follows as of June 30, 2019 (in millions, except lease term and discount rate): June 30, 2019 (1) Operating leases (2) Right-of-use assets associated with operating leases $ 184 Finance leases (3) Property, plant and equipment, gross $ 213 Accumulated amortization (104 ) Property, plant and equipment, net $ 109 Weighted average remaining lease term (in years) Operating leases 15.8 Finance leases 7.4 Weighted average discount rate Operating leases 5.1 % Finance leases 8.0 % ____________ (1) Excludes a right-of-use asset and property, plant and equipment, net of $1 million and $17 million , respectively, related to Garrison Energy Center which are included in current assets held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center. (2) The right-of-use assets associated with our operating leases as of June 30, 2019 are included in other assets on our Consolidated Condensed Balance Sheet. (3) The right-of-use assets associated with our finance leases as of June 30, 2019 are included in property, plant and equipment, net on our Consolidated Condensed Balance Sheet. Supplemental cash flow information related to our operating and finance leases is as follows for the period presented (in millions): Six Month Ended June 30, 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 13 Operating cash flows from finance leases $ 4 Financing cash flows from finance leases $ 6 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 9 Finance leases $ — As of June 30, 2019 , we have executed agreements that contain a lease with a future lease commencement date and future lease commitments of $1 million primarily related to an office lease which is scheduled to commence in September 2019. Accounting for Leases – Lessor We apply lease accounting to PPAs that meet the definition of a lease and determine lease classification treatment at commencement of the agreement. We currently do not have any contracts which are accounted for as sales-type leases or direct financing leases and all of our leases as the lessor are classified as operating leases. As part of the implementation of Topic 842, we elected the practical expedient to not reassess leases that have commenced prior to January 1, 2019. Revenue from contracts accounted for as operating leases, such as certain tolling agreements, with minimum lease rentals (capacity payments) which vary over time must be levelized. Generally, we levelize these contract revenues on a straight-line basis over the term of the contract. Our operating leases that have commenced contain terms extending through December 2034. These contracts also generally contain variable payment components based on generation volumes or operating efficiency over a period of time. Revenues associated with the variable payments are recognized over time as the goods or services are provided to the lessee. Our operating leases generally do not contain renewal or purchase options or residual value guarantees. We have elected to not separate our lease and non-lease components as the lease components reflect the predominant characteristics of these agreements. Revenue recognized related to fixed lease payments on our operating leases for the period presented is as follows (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2019 Operating Leases (1) Fixed lease payments $ 70 $ 139 ____________ (1) Revenues associated with our operating leases are included in Commodity revenue and other revenue on our Consolidated Condensed Statement of Operations. The total contractual future minimum lease rentals for our contracts that have commenced and are accounted for as operating leases at June 30, 2019 , are as follows (in millions): 2019 $ 204 2020 287 2021 261 2022 227 2023 144 Thereafter 284 Total $ 1,407 We do not recognize lease receivables associated with our operating leases as the long-lived assets subject to the lease contracts are recorded on our Consolidated Condensed Balance Sheet and are being depreciated over their estimated useful lives. Amounts recorded on our Consolidated Condensed Balance Sheet associated with the long-lived assets subject to our operating leases as of June 30, 2019 are as follows (in millions): June 30, 2019 Assets subject to contracts accounted for as operating leases Property, plant and equipment, gross $ 3,076 Accumulated depreciation (903 ) Property, plant and equipment, net (1) $ 2,173 ____________ (1) Our assets subject to contracts that are accounted for as operating leases primarily consist of our power plants subject to tolling contracts. We also record lease levelization assets and liabilities for any difference between the timing of the contractual payments made related to our operating lease contracts and revenue recognized on a straight-line basis. These balances are included in current and long-term assets and liabilities on our Consolidated Condensed Balance Sheet. Disclosures for periods prior to the adoption of Topic 842 Lessee The following is a schedule by year of future minimum lease payments under operating and capital leases as of December 31, 2018 (in millions): Operating Leases Capital Leases (1) 2019 $ 50 $ 40 2020 19 40 2021 20 38 2022 18 33 2023 17 27 Thereafter 192 92 Total minimum lease payments $ 316 270 Less: Amount representing interest 89 Present value of net minimum lease payments $ 181 ____________ (1) Includes a failed sale-leaseback transaction related to our Pasadena Power Plant. At December 31, 2018 , the asset balance for our assets under capital leases totaled approximately $715 million with accumulated amortization of $353 million . Lessor The total contractual future minimum lease rentals for our contracts accounted for as operating leases at December 31, 2018 , are as follows (in millions): 2019 $ 342 2020 261 2021 257 2022 224 2023 141 Thereafter 239 Total $ 1,464

Divestitures (Notes)

Divestitures (Notes)	6 Months Ended
	Jun. 30, 2019
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	Sale of Garrison Energy Center and RockGen Energy Center On July 10, 2019, we, through our indirect, wholly owned subsidiaries Calpine Holdings, LLC and Calpine Northbrook Project Holdings, LLC, completed the sale of 100% of our ownership interests in Garrison Energy Center LLC (“Garrison”) and RockGen Energy LLC (“RockGen”) to Cobalt Power, L.L.C. for approximately $360 million , subject to certain working capital adjustments and the execution of financial commodity contracts. Garrison owns the Garrison Energy Center, a 309 MW natural gas-fired, combined-cycle power plant located in Dover, Delaware, and RockGen owns the RockGen Energy Center, a 503 MW natural gas-fired, simple-cycle power plant located in Christiana, Wisconsin. We used the sale proceeds, together with cash on hand, to fund a dividend of $400 million to our parent, CPN Management, LP. At June 30, 2019, the assets and liabilities of Garrison and RockGen, which are part of our East segment, were classified as 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. We recorded impairment losses of $40 million and $55 million during the three and six months ended June 30, 2019 , respectively, associated with the sale to adjust the carrying value of the assets to reflect fair value less cost to sell.

Variable Interest Entities and

Variable Interest Entities and Unconsolidated Investments in Power Plants	6 Months Ended
	Jun. 30, 2019
Variable Interest Entities and Unconsolidated Investments [Abstract]
Variable interest entities and unconsolidated investments in power plants	Variable Interest Entities and Unconsolidated Investments We consolidate all of our VIEs where we have determined that we are the primary beneficiary. There were no changes to our determination of whether we are the primary beneficiary of our VIEs for the six months ended June 30, 2019 . See Note 7 in our 2018 Form 10-K for further information regarding our VIEs. VIE Disclosures Our consolidated VIEs include natural gas-fired power plants with an aggregate capacity of 7,880 MW and 7,880 MW at June 30, 2019 and December 31, 2018 , respectively. For these VIEs, we may provide other operational and administrative support through various affiliate contractual arrangements among the VIEs, Calpine Corporation and its other wholly owned subsidiaries whereby we support the VIE through the reimbursement of costs and/or the purchase and sale of energy. Other than amounts contractually required, we provided support to these VIEs in the form of cash and other contributions of nil during each of the three and six months ended June 30, 2019 and 2018 . OMEC — OMEC has a ten-year tolling agreement with SDG&E, which commenced on October 3, 2009. Under a ground lease agreement, OMEC held a put option to sell the Otay Mesa Energy Center for $280 million to SDG&E, pursuant to the terms and conditions of the agreement, which was exercisable until April 1, 2019 and SDG&E held a call option to purchase the Otay Mesa Energy Center for $377 million , which was exercisable through October 3, 2018. The call option held by SDG&E expired unexercised. OMEC has executed a new 59-month Resource Adequacy (“RA”) contract with SDG&E, which would commence on October 3, 2019. The RA contract received initial regulatory approval by the California Public Utilities Commission (“CPUC”) on February 21, 2019. This approval was subject to a 30 day appeal period from the date of the issuance of the CPUC decision. On March 27, 2019, an appeal of the CPUC decision was filed with the CPUC, which appeal was denied on August 1, 2019. As a result, we continue to work to commence the RA contract. However, in the event that we are not successful and another alternative is not reached with SDG&E prior to October 3, 2019, OMEC expects to close on the put and transfer the Otay Mesa Energy Center to SDG&E for $280 million on or about October 3, 2019, which transaction could result in a write down of the carrying value of the asset. On December 19, 2018, we refinanced the project debt associated with OMEC which lowered the aggregate debt balance to $220 million and extended the maturity to August 2024. In the event that the exercise of the OMEC put option is not rescinded, the OMEC project debt will become payable on November 3, 2019. We have concluded that we are the primary beneficiary of OMEC as we believe the activity that has the most effect on the financial performance of OMEC is operations and maintenance which is controlled by us. As a result, we consolidate OMEC. Unconsolidated VIEs and Investments in Unconsolidated Subsidiaries We have a 50% partnership interest in Greenfield LP and in Whitby. Greenfield LP and Whitby are VIEs; however, we do not have the power to direct the most significant activities of these entities and therefore do not consolidate them. Greenfield LP is a limited partnership between certain subsidiaries of ours and of Mitsui & Co., Ltd., which operates the Greenfield Energy Centre, a 1,038 MW natural gas-fired, combined-cycle power plant located in Ontario, Canada. We and Mitsui & Co., Ltd. each hold a 50% interest in Greenfield LP. Whitby is a limited partnership between certain of our subsidiaries and Atlantic Packaging Ltd., which operates the Whitby facility, a 50 MW natural gas-fired, simple-cycle cogeneration power plant located in Ontario, Canada. We and Atlantic Packaging Ltd. each hold a 50% partnership interest in Whitby. Calpine Receivables is a VIE and a bankruptcy remote entity created for the special purpose of purchasing trade accounts receivable from Calpine Solutions under the Accounts Receivable Sales Program. We have determined that we do not have the power to direct the activities of the VIE that most significantly affect the VIE’s economic performance nor the obligation to absorb losses or receive benefits from the VIE. Accordingly, we have determined that we are not the primary beneficiary of Calpine Receivables because we do not have the power to affect its financial performance as the unaffiliated financial institutions that purchase the receivables from Calpine Receivables control the selection criteria of the receivables sold and appoint the servicer of the receivables which controls management of default. Thus, we do not consolidate Calpine Receivables in our Consolidated Condensed Financial Statements and use the equity method of accounting to record our net interest in Calpine Receivables. We account for these entities under the equity method of accounting and include our net equity interest in investments in unconsolidated subsidiaries on our Consolidated Condensed Balance Sheets. At June 30, 2019 and December 31, 2018 , our equity method investments included on our Consolidated Condensed Balance Sheets were comprised of the following (in millions): Ownership Interest as of June 30, 2019 June 30, 2019 December 31, 2018 Greenfield LP (1) 50% $ 56 $ 55 Whitby 50% 10 15 Calpine Receivables 100% 5 6 Total investments in unconsolidated subsidiaries $ 71 $ 76 ____________ (1) Includes our share of accumulated other comprehensive income/loss related to interest rate hedging instruments associated with our unconsolidated subsidiary Greenfield LP’s debt. Our risk of loss related to our investments in Greenfield LP and Whitby is limited to our investment balance. Our risk of loss related to our investment in Calpine Receivables is $67 million which consists of our notes receivable from Calpine Receivables at June 30, 2019 and our initial investment associated with Calpine Receivables. See Note 12 for further information associated with our related party activity with Calpine Receivables. Holders of the debt of our unconsolidated investments do not have recourse to Calpine Corporation and its other subsidiaries; therefore, the debt of our unconsolidated investments is not reflected on our Consolidated Condensed Balance Sheets. At June 30, 2019 and December 31, 2018 , Greenfield LP’s debt was approximately $304 million and $ 301 million , respectively, and based on our pro rata share of our investment in Greenfield LP, our share of such debt would be approximately $152 million and $ 151 million at June 30, 2019 and December 31, 2018 , respectively. Our equity interest in the net income from our investments in unconsolidated subsidiaries for the three and six months ended June 30, 2019 and 2018 , is recorded in (income) from unconsolidated subsidiaries. The following table sets forth details of our (income) from unconsolidated subsidiaries for the periods indicated (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Greenfield LP $ (4 ) $ (2 ) $ (6 ) $ (4 ) Whitby (2 ) (4 ) (6 ) (8 ) Calpine Receivables 1 1 1 1 Total $ (5 ) $ (5 ) $ (11 ) $ (11 ) Distributions from Greenfield LP were nil during each of the three and six months ended June 30, 2019 and 2018 . Distributions from Whitby were nil and $11 million during the three and six months ended June 30, 2019 , respectively, and $2 million and $5 million during the three and six months ended June 30, 2018 , respectively. We did not have material distributions from our investment in Calpine Receivables for the three and six months ended June 30, 2019 and 2018 . Inland Empire Energy Center Put and Call Options — We held a call option to purchase the Inland Empire Energy Center (a 775 MW natural gas-fired power plant located in California) at predetermined prices from GE that could be exercised between years 2017 and 2024 . GE held a put option whereby they could require us to purchase the power plant, if certain plant performance criteria were met by 2025 . On February 1, 2019, we entered into an agreement with GE, which among other things, terminated our call option and GE’s put option related to the Inland Empire Energy Center. As per this agreement, we will take ownership of the facility site and certain remaining site infrastructure and equipment after closure and decommissioning of the facility at a future date, until such time GE continues to own, operate and maintain the power plant, including directing any closure activities. As GE continues to direct all such significant activities of the power plant, we have determined that we no longer hold any variable interests in the Inland Empire Energy Center and it is not a VIE to Calpine.

Debt

Debt	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt Our debt at June 30, 2019 and December 31, 2018 , was as follows (in millions): June 30, 2019 December 31, 2018 Senior Unsecured Notes $ 2,990 $ 3,036 First Lien Term Loans 2,979 2,976 First Lien Notes 2,402 2,400 Project financing, notes payable and other 1,229 1,264 CCFC Term Loan 971 974 Finance lease obligations 78 105 Corporate Revolving Facility 75 30 Subtotal 10,724 10,785 Less: Current maturities 263 637 Total long-term debt $ 10,461 $ 10,148 Our effective interest rate on our consolidated debt, excluding the effects of capitalized interest and mark-to-market gains (losses) on interest rate hedging instruments, increased to 5.9% for the six months ended June 30, 2019 , from 5.7% for the same period in 2018. Since the fourth quarter of 2018, we have cumulatively repurchased $438 million in aggregate principal of our Senior Unsecured Notes for $399 million . Senior Unsecured Notes The amounts outstanding under our Senior Unsecured Notes are summarized in the table below (in millions): June 30, 2019 December 31, 2018 2023 Senior Unsecured Notes $ 1,228 $ 1,227 2024 Senior Unsecured Notes 589 599 2025 Senior Unsecured Notes 1,173 1,210 Total Senior Unsecured Notes $ 2,990 $ 3,036 During the six months ended June 30, 2019, we repurchased $48 million in aggregate principal of our Senior Unsecured Notes for $44 million . In connection with the repurchases, we recorded approximately $4 million in gain on extinguishment of debt. First Lien Term Loans The amounts outstanding under our senior secured First Lien Term Loans are summarized in the table below (in millions): June 30, 2019 December 31, 2018 2019 First Lien Term Loan $ — $ 389 2023 First Lien Term Loans 535 1,059 2024 First Lien Term Loan 1,522 1,528 2026 First Lien Term Loan 922 — Total First Lien Term Loans $ 2,979 $ 2,976 On April 5, 2019, we entered into a $950 million first lien senior secured term loan which bears interest, at our option, at either (i) the Base Rate, equal to the highest of (a) the Federal Funds Effective Rate plus 0.50% per annum, (b) the Prime Rate or (c) the Eurodollar Rate for a one month interest period plus 1.0% (in each case, as such terms are defined in the credit agreement), plus an applicable margin of 1.75% , or (ii) LIBOR plus 2.75% per annum (with a 0% LIBOR floor) and matures on April 5, 2026. An aggregate amount equal to 0.25% of the aggregate principal amount of the 2026 First Lien Term Loan is payable at the end of each quarter with the remaining balance payable on the maturity date. We paid an upfront fee of an amount equal to 1.0% of the aggregate principal amount of the 2026 First Lien Term Loan, which is structured as original issue discount and recorded approximately $7 million in debt issuance costs during the second quarter of 2019 related to the issuance of our 2026 First Lien Term Loan. The 2026 First Lien Term Loan contains substantially similar covenants, qualifications, exceptions and limitations as our First Lien Term Loans and First Lien Notes. We used the proceeds from our 2026 First Lien Term Loan to repay our 2019 First Lien Term Loan and a portion of our 2023 First Lien Term Loans with a maturity date in January 2023 and recorded approximately $3 million in loss on extinguishment of debt during the second quarter of 2019 associated with the repayment. First Lien Notes The amounts outstanding under our senior secured First Lien Notes are summarized in the table below (in millions): June 30, 2019 December 31, 2018 2022 First Lien Notes $ 744 $ 743 2024 First Lien Notes 487 486 2026 First Lien Notes 1,171 1,171 Total First Lien Notes $ 2,402 $ 2,400 Project Financing, Notes Payable and Other On January 29, 2019, Pacific Gas and Electric Company (“PG&E”) and PG&E Corporation each filed voluntary petitions for relief under Chapter 11. Our power plants that sell energy and energy-related products to PG&E through PPAs, include Russell City Energy Center and Los Esteros Critical Energy Facility. Since the bankruptcy filing, we have received all material payments under the PPAs, either directly or through the application of collateral. As a result of PG&E’s bankruptcy, we are currently unable to make distributions from our Russell City and Los Esteros projects in accordance with the terms of the project debt agreements associated with each related project. In July 2019, we executed forbearance agreements associated with the Russell City and Los Esteros project debt agreements, under which the lenders have agreed to forbear enforcement of their rights and remedies, including the ability to accelerate the repayment of borrowings outstanding, otherwise arising because PG&E did not assume our PPAs during the first 180 days of PG&E’s bankruptcy proceeding. The forbearance agreements are effective for rolling 90-day periods, so long as we continue to meet certain conditions, including that the PPAs have not been rejected and there are no other defaults under the project debt agreements or the forbearance agreements. We may be required to reclassify $362 million of Russell City and Los Esteros long-term project debt outstanding at June 30, 2019 to a current liability in a future period. We continue to monitor the bankruptcy proceedings and are assessing our options. In the event that the exercise of the OMEC put option is not rescinded, the OMEC project debt will become payable on November 3, 2019. See Note 5 for further information related to the OMEC put option. Corporate Revolving Facility and Other Letter of Credit Facilities The table below represents amounts issued under our letter of credit facilities at June 30, 2019 and December 31, 2018 (in millions): June 30, 2019 December 31, 2018 Corporate Revolving Facility (1) $ 585 $ 693 CDHI (2) 30 251 Various project financing facilities 227 228 Other corporate facilities (3) 293 193 Total $ 1,135 $ 1,365 ____________ (1) The Corporate Revolving Facility represents our primary revolving facility. On April 5, 2019, we amended our Corporate Revolving Facility to increase the capacity by approximately $330 million from $1.69 billion to approximately $2.02 billion . (2) Pursuant to the terms and conditions of the CDHI credit agreement, the capacity under the CDHI letter of credit facility was reduced to $125 million on June 28, 2019. The decrease in capacity did not have a material effect on our liquidity as alternative sources of liquidity are available. (3) We have three unsecured letter of credit facilities with two third-party financial institutions totaling approximately $300 million at June 30, 2019 . Fair Value of Debt We record our debt instruments based on contractual terms, net of any applicable premium or discount and debt issuance costs. The following table details the fair values and carrying values of our debt instruments at June 30, 2019 and December 31, 2018 (in millions): June 30, 2019 December 31, 2018 Fair Value Carrying Value Fair Value Carrying Value Senior Unsecured Notes $ 3,011 $ 2,990 $ 2,803 $ 3,036 First Lien Term Loans 3,013 2,979 2,877 2,976 First Lien Notes 2,462 2,402 2,299 2,400 Project financing, notes payable and other (1) 1,136 1,153 1,209 1,188 CCFC Term Loan 980 971 938 974 Corporate Revolving Facility 75 75 30 30 Total $ 10,677 $ 10,570 $ 10,156 $ 10,604 ____________ (1) Excludes an agreement that is accounted for as a failed sale-leaseback transaction under U.S. GAAP. Our Senior Unsecured Notes, First Lien Term Loans, First Lien Notes, CCFC Term Loan and Corporate Revolving Facility are categorized as level 2 within the fair value hierarchy. Our project financing, notes payable and other debt instruments are categorized as level 3 within the fair value hierarchy. We do not have any debt instruments with fair value measurements categorized as level 1 within the fair value hierarchy.

Assets and Liabilities with Rec

Assets and Liabilities with Recurring Fair Value Measurements	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Assets and Liabilities with Recurring Fair Value Measurements	Assets and Liabilities with Recurring Fair Value Measurements Cash Equivalents — Highly liquid investments which meet the definition of cash equivalents, primarily investments in money market accounts and other interest-bearing accounts, are included in both our cash and cash equivalents and our restricted cash on our Consolidated Condensed Balance Sheets. Certain of our money market accounts invest in U.S. Treasury securities or other obligations issued or guaranteed by the U.S. Government, its agencies or instrumentalities. We do not have any cash equivalents invested in institutional prime money market funds which require use of a floating net asset value and are subject to liquidity fees and redemption restrictions. Certain of our cash equivalents are classified within level 1 of the fair value hierarchy. Derivatives — The primary factors affecting the fair value of our derivative instruments at any point in time are the volume of open derivative positions (MMBtu, MWh and $ notional amounts); changing commodity market prices, primarily for power and natural gas; our credit standing and that of our counterparties and customers for energy commodity derivatives; and prevailing interest rates for our interest rate hedging instruments. Prices for power and natural gas and interest rates are volatile, which can result in material changes in the fair value measurements reported in our financial statements in the future. We utilize market data, such as pricing services and broker quotes, and assumptions that we believe market participants would use in pricing our assets or liabilities including assumptions about the risks inherent to the inputs in the valuation technique. These inputs can be either readily observable, market corroborated or generally unobservable. The market data obtained from broker pricing services is evaluated to determine the nature of the quotes obtained and, where accepted as a reliable quote, used to validate our assessment of fair value. We use other qualitative assessments to determine the level of activity in any given market. We primarily apply the market approach and income approach for recurring fair value measurements and utilize what we believe to be the best available information. We utilize valuation techniques that seek to maximize the use of observable inputs and minimize the use of unobservable inputs. We classify fair value balances based on the observability of those inputs. The fair value of our derivatives includes consideration of our credit standing, the credit standing of our counterparties and customers and the effect of credit enhancements, if any. We have also recorded credit reserves in the determination of fair value based on our expectation of how market participants would determine fair value. Such valuation adjustments are generally based on market evidence, if available, or our best estimate. Our level 1 fair value derivative instruments primarily consist of power and natural gas swaps, futures and options traded on the NYMEX or Intercontinental Exchange. Our level 2 fair value derivative instruments primarily consist of interest rate hedging instruments and OTC power and natural gas forwards for which market-based pricing inputs in the principal or most advantageous market are representative of executable prices for market participants. These inputs are observable at commonly quoted intervals for substantially the full term of the instruments. In certain instances, our level 2 derivative instruments may utilize models to measure fair value. These models are industry-standard models, including the Black-Scholes option-pricing model, that incorporate various assumptions, including quoted interest rates, correlation, volatility, as well as other relevant economic measures. Substantially all of these assumptions are observable in the marketplace throughout the full term of the instrument, can be derived from observable data or are supported by observable levels at which transactions are executed in the marketplace. Our level 3 fair value derivative instruments may consist of OTC power and natural gas forwards and options where pricing inputs are unobservable, as well as other complex and structured transactions primarily for the sale and purchase of power and natural gas to both wholesale counterparties and retail customers. Complex or structured transactions are tailored to our customers’ needs and can introduce the need for internally-developed model inputs which might not be observable in or corroborated by the market. When such inputs have a significant effect on the measurement of fair value, the instrument is categorized in level 3. Our valuation models may incorporate historical correlation information and extrapolate available broker and other information to future periods. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement at period end. Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect our estimate of the fair value of our assets and liabilities and their placement within the fair value hierarchy levels. The following tables present our financial assets and liabilities that were accounted for at fair value on a recurring basis as of June 30, 2019 and December 31, 2018 , by level within the fair value hierarchy: Assets and Liabilities with Recurring Fair Value Measures as of June 30, 2019 Level 1 Level 2 Level 3 Total (in millions) Assets: Cash equivalents (1) $ 165 $ — $ — $ 165 Commodity instruments: Commodity exchange traded derivatives contracts 1,089 — — 1,089 Commodity forward contracts (2) — 350 322 672 Interest rate hedging instruments — 6 — 6 Effect of netting and allocation of collateral (3)(4) (1,089 ) (243 ) (20 ) (1,352 ) Total assets $ 165 $ 113 $ 302 $ 580 Liabilities: Commodity instruments: Commodity exchange traded derivatives contracts $ 1,179 $ — $ — $ 1,179 Commodity forward contracts (2) — 474 96 570 Interest rate hedging instruments — 33 — 33 Effect of netting and allocation of collateral (3)(4) (1,179 ) (298 ) (21 ) (1,498 ) Total liabilities $ — $ 209 $ 75 $ 284 Assets and Liabilities with Recurring Fair Value Measures as of December 31, 2018 Level 1 Level 2 Level 3 Total (in millions) Assets: Cash equivalents (1) $ 168 $ — $ — $ 168 Commodity instruments: Commodity exchange traded derivatives contracts 933 — — 933 Commodity forward contracts (2) — 338 212 550 Interest rate hedging instruments — 40 — 40 Effect of netting and allocation of collateral (3)(4) (933 ) (262 ) (26 ) (1,221 ) Total assets $ 168 $ 116 $ 186 $ 470 Liabilities: Commodity instruments: Commodity exchange traded derivatives contracts $ 932 $ — $ — $ 932 Commodity forward contracts (2) — 549 220 769 Interest rate hedging instruments — 10 — 10 Effect of netting and allocation of collateral (3)(4) (932 ) (310 ) (26 ) (1,268 ) Total liabilities $ — $ 249 $ 194 $ 443 ___________ (1) At June 30, 2019 and December 31, 2018 , we had cash equivalents of $16 million and $23 million included in cash and cash equivalents and $149 million and $145 million included in restricted cash, respectively. (2) Includes OTC swaps and options. (3) We offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation; therefore, amounts recognized for the right to reclaim, or the obligation to return, cash collateral are presented net with the corresponding derivative instrument fair values. See Note 8 for further discussion of our derivative instruments subject to master netting arrangements. (4) Cash collateral posted with (received from) counterparties allocated to level 1, level 2 and level 3 derivative instruments totaled $90 million , $55 million and $1 million , respectively, at June 30, 2019 . Cash collateral posted with (received from) counterparties allocated to level 1, level 2 and level 3 derivative instruments totaled $(1) million , $48 million and nil , respectively, at December 31, 2018 . At June 30, 2019 and December 31, 2018 , the derivative instruments classified as level 3 primarily included commodity contracts, which are classified as level 3 because the contract terms relate to a delivery location or tenor for which observable market rate information is not available. The fair value of the net derivative position classified as level 3 is predominantly driven by market commodity prices. The following table presents quantitative information for the unobservable inputs used in our most significant level 3 fair value measurements at June 30, 2019 and December 31, 2018 : Quantitative Information about Level 3 Fair Value Measurements June 30, 2019 Fair Value, Net Asset Significant Unobservable (Liability) Valuation Technique Input Range (in millions) Power Contracts (1) $ 190 Discounted cash flow Market price (per MWh) $ 7.09 — $123.34 /MWh Power Congestion Products $ 18 Discounted cash flow Market price (per MWh) $ (8.63 ) — $11.48 /MWh Natural Gas Contracts $ 6 Discounted cash flow Market price (per MMBtu) $ 0.61 — $9.75 /MMBtu December 31, 2018 Fair Value, Net Asset Significant Unobservable (Liability) Valuation Technique Input Range (in millions) Power Contracts (1) $ 36 Discounted cash flow Market price (per MWh) $ 2.12 — $227.98 /MWh Power Congestion Products $ 26 Discounted cash flow Market price (per MWh) $ (11.71 ) — $11.88 /MWh Natural Gas Contracts $ (73 ) Discounted cash flow Market price (per MMBtu) $ 0.75 — $8.87 /MMBtu ___________ (1) Power contracts include power and heat rate instruments classified as level 3 in the fair value hierarchy. The following table sets forth a reconciliation of changes in the fair value of our net derivative assets (liabilities) classified as level 3 in the fair value hierarchy for the periods indicated (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Balance, beginning of period $ 105 $ 129 $ (8 ) $ 197 Realized and mark-to-market gains (losses): Included in net income (loss): Included in operating revenues (1) 152 31 197 (28 ) Included in fuel and purchased energy expense (2) 1 18 2 15 Change in collateral (1 ) 1 1 (1 ) Purchases, Issuances and settlements: Purchases 1 5 3 9 Issuances (1 ) — (1 ) — Settlements (35 ) (42 ) 28 (53 ) Transfers in and/or out of level 3 (3) : Transfers into level 3 (4) 6 (1 ) 7 (1 ) Transfers out of level 3 (5) (1 ) (10 ) (2 ) (7 ) Balance, end of period $ 227 $ 131 $ 227 $ 131 Change in unrealized gains (losses) relating to instruments still held at end of period $ 153 $ 49 $ 199 $ (13 ) ___________ (1) For power contracts and other power-related products, included on our Consolidated Condensed Statements of Operations. (2) For natural gas and power contracts, swaps and options, included on our Consolidated Condensed Statements of Operations. (3) We transfer amounts among levels of the fair value hierarchy as of the end of each period. There were no transfers into or out of level 1 for each of the three and six months ended June 30, 2019 and 2018 . (4) We had $6 million in gains and $(1) million in losses transferred out of level 2 into level 3 for the three months ended June 30, 2019 and 2018 , respectively, and $7 million in gains and $(1) million in losses transferred out of level 2 into level 3 for the six months ended June 30, 2019 and 2018 , respectively, due to changes in market liquidity in various power markets. (5) We had $1 million and $10 million in gains transferred out of level 3 into level 2 for the three months ended June 30, 2019 and 2018 , respectively, and $2 million and $7 million in gains transferred out of level 3 into level 2 for the six months ended June 30, 2019 and 2018 , respectively, due to changes in market liquidity in various power markets.

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Types of Derivative Instruments and Volumetric Information Commodity Instruments — We are exposed to changes in prices for the purchase and sale of power, natural gas, fuel oil, environmental products and other energy commodities. We use derivatives, which include physical commodity contracts and financial commodity instruments such as OTC and exchange traded swaps, futures, options, forward agreements and instruments that settle on the power price to natural gas price relationships (Heat Rate swaps and options) or instruments that settle on power or natural gas price relationships between delivery points for the purchase and sale of power and natural gas to attempt to maximize the risk-adjusted returns by economically hedging a portion of the commodity price risk associated with our assets. By entering into these transactions, we are able to economically hedge a portion of our Spark Spread at estimated generation and prevailing price levels. We also engage in limited trading activities related to our commodity derivative portfolio as authorized by our Board of Directors and monitored by our Chief Risk Officer and Risk Management Committee of senior management. These transactions are executed primarily for the purpose of providing improved price and price volatility discovery, greater market access, and profiting from our market knowledge, all of which benefit our asset hedging activities. Our trading results were not material for each of the three and six months ended June 30, 2019 and 2018 . Interest Rate Hedging Instruments — A portion of our debt is indexed to base rates, primarily LIBOR. We have historically used interest rate hedging instruments to adjust the mix between fixed and variable rate debt to hedge our interest rate risk for potential adverse changes in interest rates. As of June 30, 2019 , the maximum length of time over which we were hedging using interest rate hedging instruments designated as cash flow hedges was 6 years. As of June 30, 2019 and December 31, 2018 , the net forward notional buy (sell) position of our outstanding commodity derivative instruments that did not qualify or were not designated under the normal purchase normal sale exemption and our interest rate hedging instruments were as follows: Derivative Instruments Notional Amounts June 30, 2019 December 31, 2018 Unit of Measure Power (181 ) (161 ) Million MWh Natural gas 1,048 1,045 Million MMBtu Environmental credits 13 13 Million Tonnes Interest rate hedging instruments $ 4.3 $ 4.5 Billion U.S. dollars Certain of our derivative instruments contain credit risk-related contingent provisions that require us to maintain collateral balances consistent with our credit ratings. If our credit rating were to be downgraded, it could require us to post additional collateral or could potentially allow our counterparty to request immediate, full settlement on certain derivative instruments in liability positions. The aggregate fair value of our derivative liabilities with credit risk-related contingent provisions as of June 30, 2019 , was $230 million for which we have posted collateral of $171 million by posting margin deposits, letters of credit or granting additional first priority liens on the assets currently subject to first priority liens under our First Lien Notes, First Lien Term Loans and Corporate Revolving Facility. However, if our credit rating were downgraded by one notch from its current level, we estimate that additional collateral of $5 million related to our derivative liabilities would be required and that no counterparty could request immediate, full settlement. Accounting for Derivative Instruments We recognize all derivative instruments that qualify for derivative accounting treatment as either assets or liabilities and measure those instruments at fair value unless they qualify for, and we elect, the normal purchase normal sale exemption. For transactions in which we elect the normal purchase normal sale exemption, gains and losses are not reflected on our Consolidated Condensed Statements of Operations until the period of delivery. Revenues and expenses derived from instruments that qualified for hedge accounting or represent an economic hedge are recorded in the same financial statement line item as the item being hedged. Hedge accounting requires us to formally document, designate and assess the effectiveness of transactions that receive hedge accounting. We present the cash flows from our derivatives in the same category as the item being hedged (or economically hedged) within operating activities on our Consolidated Condensed Statements of Cash Flows unless they contain an other-than-insignificant financing element in which case their cash flows are classified within financing activities. Cash Flow Hedges — We currently apply hedge accounting to our interest rate hedging instruments. We report the mark-to-market gain or loss on our interest rate hedging instruments designated and qualifying as a cash flow hedging instrument as a component of OCI and reclassify such gains and losses into earnings in the same period during which the hedged forecasted transaction affects earnings. Prior to January 1, 2019, gains and losses due to ineffectiveness on interest rate hedging instruments were recognized in earnings as a component of interest expense. Upon the adoption of Accounting Standards Update 2017-12 on January 1, 2019, hedge ineffectiveness is no longer separately measured and recorded in earnings. If it is determined that the forecasted transaction is no longer probable of occurring, then hedge accounting will be discontinued prospectively and future changes in fair value will be recorded in earnings. If the hedging instrument is terminated or de-designated prior to the occurrence of the hedged forecasted transaction, the net accumulated gain or loss associated with the changes in fair value of the hedge instrument remains deferred in AOCI until such time as the forecasted transaction affects earnings or until it is determined that the forecasted transaction is probable of not occurring. Derivatives Not Designated as Hedging Instruments — We enter into power, natural gas, interest rate, environmental product and fuel oil transactions that primarily act as economic hedges to our asset and interest rate portfolio, but either do not qualify as hedges under the hedge accounting guidelines or qualify under the hedge accounting guidelines and the hedge accounting designation has not been elected. Changes in fair value of commodity derivatives not designated as hedging instruments are recognized currently in earnings and are separately stated on our Consolidated Condensed Statements of Operations in mark-to-market gain/loss as a component of operating revenues (for physical and financial power and Heat Rate and commodity option activity) and fuel and purchased energy expense (for physical and financial natural gas, power, environmental product and fuel oil activity). Changes in fair value of interest rate derivatives not designated as hedging instruments are recognized currently in earnings as interest expense. Derivatives Included on Our Consolidated Condensed Balance Sheets We offset fair value amounts associated with our derivative instruments and related cash collateral and margin deposits on our Consolidated Condensed Balance Sheets that are executed with the same counterparty under master netting arrangements. Our netting arrangements include a right to set off or net together purchases and sales of similar products in the margining or settlement process. In some instances, we have also negotiated cross commodity netting rights which allow for the net presentation of activity with a given counterparty regardless of product purchased or sold. We also post and/or receive cash collateral in support of our derivative instruments which may also be subject to a master netting arrangement with the same counterparty. The following tables present the fair values of our derivative instruments and our net exposure after offsetting amounts subject to a master netting arrangement with the same counterparty to our derivative instruments recorded on our Consolidated Condensed Balance Sheets by location and hedge type at June 30, 2019 and December 31, 2018 (in millions): June 30, 2019 Gross Amounts of Assets and (Liabilities) Gross Amounts Offset on the Consolidated Condensed Balance Sheets Net Amount Presented on the Consolidated Condensed Balance Sheets (1) Derivative assets: Commodity exchange traded derivatives contracts $ 861 $ (861 ) $ — Commodity forward contracts 388 (188 ) 200 Interest rate hedging instruments 5 (3 ) 2 Total current derivative assets (2) $ 1,254 $ (1,052 ) $ 202 Commodity exchange traded derivatives contracts 228 (228 ) — Commodity forward contracts 284 (71 ) 213 Interest rate hedging instruments 1 (1 ) — Total long-term derivative assets (2) $ 513 $ (300 ) $ 213 Total derivative assets $ 1,767 $ (1,352 ) $ 415 Derivative (liabilities): Commodity exchange traded derivatives contracts $ (861 ) $ 861 $ — Commodity forward contracts (393 ) 234 (159 ) Interest rate hedging instruments (9 ) 3 (6 ) Total current derivative (liabilities) (2) $ (1,263 ) $ 1,098 $ (165 ) Commodity exchange traded derivatives contracts (318 ) 318 — Commodity forward contracts (177 ) 81 (96 ) Interest rate hedging instruments (24 ) 1 (23 ) Total long-term derivative (liabilities) (2) $ (519 ) $ 400 $ (119 ) Total derivative liabilities $ (1,782 ) $ 1,498 $ (284 ) Net derivative assets (liabilities) $ (15 ) $ 146 $ 131 December 31, 2018 Gross Amounts of Assets and (Liabilities) Gross Amounts Offset on the Consolidated Condensed Balance Sheets Net Amount Presented on the Consolidated Condensed Balance Sheets (1) Derivative assets: Commodity exchange traded derivatives contracts $ 820 $ (820 ) $ — Commodity forward contracts 341 (229 ) 112 Interest rate hedging instruments 30 — 30 Total current derivative assets (3) $ 1,191 $ (1,049 ) $ 142 Commodity exchange traded derivatives contracts 113 (113 ) — Commodity forward contracts 209 (59 ) 150 Interest rate hedging instruments 10 — 10 Total long-term derivative assets (3) $ 332 $ (172 ) $ 160 Total derivative assets $ 1,523 $ (1,221 ) $ 302 Derivative (liabilities): Commodity exchange traded derivatives contracts $ (764 ) $ 764 $ — Commodity forward contracts (576 ) 277 (299 ) Interest rate hedging instruments (4 ) — (4 ) Total current derivative (liabilities) (3) $ (1,344 ) $ 1,041 $ (303 ) Commodity exchange traded derivatives contracts (168 ) 168 — Commodity forward contracts (193 ) 59 (134 ) Interest rate hedging instruments (6 ) — (6 ) Total long-term derivative (liabilities) (3) $ (367 ) $ 227 $ (140 ) Total derivative liabilities $ (1,711 ) $ 1,268 $ (443 ) Net derivative assets (liabilities) $ (188 ) $ 47 $ (141 ) ____________ (1) At June 30, 2019 and December 31, 2018 , we had $142 million and $244 million , respectively, of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets primarily related to initial margin requirements. (2) At June 30, 2019 , current and long-term derivative assets are shown net of collateral of $(27) million and $(3) million , respectively, and current and long-term derivative liabilities are shown net of collateral of $72 million and $104 million , respectively. (3) At December 31, 2018 , current and long-term derivative assets are shown net of collateral of $(58) million and $(8) million , respectively, and current and long-term derivative liabilities are shown net of collateral of $49 million and $64 million , respectively. June 30, 2019 December 31, 2018 Fair Value of Derivative Assets Fair Value of Derivative Liabilities Fair Value of Derivative Assets Fair Value of Derivative Liabilities Derivatives designated as cash flow hedging instruments: Interest rate hedging instruments $ 2 $ 27 $ 40 $ 10 Total derivatives designated as cash flow hedging instruments $ 2 $ 27 $ 40 $ 10 Derivatives not designated as hedging instruments: Commodity instruments $ 413 $ 255 $ 262 $ 433 Interest rate hedging instruments — 2 — — Total derivatives not designated as hedging instruments $ 413 $ 257 $ 262 $ 433 Total derivatives $ 415 $ 284 $ 302 $ 443 Derivatives Included on Our Consolidated Condensed Statements of Operations Changes in the fair values of our derivative instruments are reflected either in cash for option premiums paid or collected, in OCI, net of tax, for derivative instruments which qualify for and we have elected cash flow hedge accounting treatment, or on our Consolidated Condensed Statements of Operations as a component of mark-to-market activity within our earnings. The following tables detail the components of our total activity for both the net realized gain (loss) and the net mark-to-market gain (loss) recognized from our derivative instruments in earnings and where these components were recorded on our Consolidated Condensed Statements of Operations for the periods indicated (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Realized gain (loss) (1)(2) Commodity derivative instruments $ 58 $ 69 $ 169 $ 66 Total realized gain (loss) $ 58 $ 69 $ 169 $ 66 Mark-to-market gain (loss) (3) Commodity derivative instruments $ 187 $ 188 $ 233 $ (183 ) Interest rate hedging instruments (1 ) 1 (2 ) 3 Total mark-to-market gain (loss) $ 186 $ 189 $ 231 $ (180 ) Total activity, net $ 244 $ 258 $ 400 $ (114 ) ___________ (1) Does not include the realized value associated with derivative instruments that settle through physical delivery. (2) Includes amortization of acquisition date fair value of financial derivative activity related to the acquisition of Champion Energy and Calpine Solutions. (3) In addition to changes in market value on derivatives not designated as hedges, changes in mark-to-market gain (loss) also includes adjustments to reflect changes in credit default risk exposure. Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Realized and mark-to-market gain (loss) (1) Derivatives contracts included in operating revenues (2)(3) $ 541 $ 183 $ 578 $ (176 ) Derivatives contracts included in fuel and purchased energy expense (2)(3) (296 ) 74 (176 ) 59 Interest rate hedging instruments included in interest expense (1 ) 1 (2 ) 3 Total activity, net $ 244 $ 258 $ 400 $ (114 ) ___________ (1) In addition to changes in market value on derivatives not designated as hedges, changes in mark-to-market gain (loss) also includes adjustments to reflect changes in credit default risk exposure. (2) Does not include the realized value associated with derivative instruments that settle through physical delivery. (3) Includes amortization of acquisition date fair value of financial derivative activity related to the acquisition of Champion Energy and Calpine Solutions. Derivatives Included in OCI and AOCI The following table details the effect of our net derivative instruments that qualified for hedge accounting treatment and are included in OCI and AOCI for the periods indicated (in millions): Three Months Ended June 30, Three Months Ended June 30, Gain (Loss) Recognized in OCI Gain (Loss) Reclassified from AOCI into Income (3)(4) 2019 2018 2019 2018 Affected Line Item on the Consolidated Condensed Statements of Operations Interest rate hedging instruments (1)(2) $ (32 ) $ 15 $ 3 $ — Interest expense Total $ (32 ) $ 15 $ 3 $ — Six Months Ended June 30, Six Months Ended June 30, Gain (Loss) Recognized in OCI Gain (Loss) Reclassified from AOCI into Income (3)(4) 2019 2018 2019 2018 Affected Line Item on the Consolidated Condensed Statements of Operations Interest rate hedging instruments (1)(2) $ (57 ) $ 69 $ 5 $ (6 ) Interest expense Interest rate hedging instruments (1)(2) — 1 — (1 ) Depreciation and amortization expense Total $ (57 ) $ 70 $ 5 $ (7 ) ____________ (1) We recorded $1 million in gains on hedge ineffectiveness related to our interest rate hedging instruments designated as cash flow hedges during each of the three and six months ended June 30, 2018 . Upon the adoption of Accounting Standards Update 2017-12 on January 1, 2019, hedge ineffectiveness is no longer separately measured and recorded in earnings. (2) We recorded an income tax benefit of $1 million and $7 million for the three months ended June 30, 2019 and 2018 , respectively, and income tax benefit of $1 million and income tax expense of $4 million for the six months ended June 30, 2019 and 2018 , respectively, in AOCI related to our cash flow hedging activities. (3) Cumulative cash flow hedge losses attributable to Calpine, net of tax, remaining in AOCI were $89 million and $34 million at June 30, 2019 and December 31, 2018 , respectively. Cumulative cash flow hedge losses attributable to the noncontrolling interest, net of tax, remaining in AOCI were $4 million and $3 million at June 30, 2019 and December 31, 2018 , respectively. (4) Includes losses (gains) of nil that were reclassified from AOCI to interest expense for the three months ended June 30, 2019 and 2018 , and losses of $1 million and nil that were reclassified from AOCI to interest expense for the six months ended June 30, 2019 and 2018 , respectively, where the hedged transactions became probable of not occurring. We estimate that pre-tax net losses of $20 million would be reclassified from AOCI into interest expense during the next 12 months as the hedged transactions settle; however, the actual amounts that will be reclassified will likely vary based on changes in interest rates. Therefore, we are unable to predict what the actual reclassification from AOCI into earnings (positive or negative) will be for the next 12 months.

Use of Collateral

Use of Collateral	6 Months Ended
	Jun. 30, 2019
Use of Collateral [Abstract]
Use of Collateral [Text Block]	Use of Collateral We use margin deposits, prepayments and letters of credit as credit support with and from our counterparties for commodity procurement and risk management activities. In addition, we have granted additional first priority liens on the assets currently subject to first priority liens under various debt agreements as collateral under certain of our power and natural gas agreements and certain of our interest rate hedging instruments in order to reduce the cash collateral and letters of credit that we would otherwise be required to provide to the counterparties under such agreements. The counterparties under such agreements share the benefits of the collateral subject to such first priority liens pro rata with the lenders under our various debt agreements. The table below summarizes the balances outstanding under margin deposits, natural gas and power prepayments, and exposure under letters of credit and first priority liens for commodity procurement and risk management activities as of June 30, 2019 and December 31, 2018 (in millions): June 30, 2019 December 31, 2018 Margin deposits (1) $ 373 $ 343 Natural gas and power prepayments 34 31 Total margin deposits and natural gas and power prepayments with our counterparties (2) $ 407 $ 374 Letters of credit issued $ 900 $ 1,166 First priority liens under power and natural gas agreements 42 92 First priority liens under interest rate hedging instruments 29 10 Total letters of credit and first priority liens with our counterparties $ 971 $ 1,268 Margin deposits posted with us by our counterparties (1)(3) $ 85 $ 52 Letters of credit posted with us by our counterparties 31 27 Total margin deposits and letters of credit posted with us by our counterparties $ 116 $ 79 ___________ (1) We offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation; therefore, amounts recognized for the right to reclaim, or the obligation to return, cash collateral are presented net with the corresponding derivative instrument fair values. See Note 8 for further discussion of our derivative instruments subject to master netting arrangements. (2) At June 30, 2019 and December 31, 2018 , $162 million and $79 million , respectively, were included in current and long-term derivative assets and liabilities, $237 million and $286 million , respectively, were included in margin deposits and other prepaid expense and $8 million and $9 million , respectively, were included in other assets on our Consolidated Condensed Balance Sheets. (3) At June 30, 2019 and December 31, 2018 , $16 million and $32 million , respectively, were included in current and long-term derivative assets and liabilities, $28 million and $20 million , respectively, were included in other current liabilities and $41 million and nil , respectively, were included in other long-term liabilities on our Consolidated Condensed Balance Sheets. Future collateral requirements for cash, first priority liens and letters of credit may increase or decrease based on the extent of our involvement in hedging and optimization contracts, movements in commodity prices, and also based on our credit ratings and general perception of creditworthiness in our market.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income Tax Expense (Benefit) The table below shows our consolidated income tax expense (benefit) and our effective tax rates for the periods indicated (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Income tax expense (benefit) $ 9 $ (158 ) $ 19 $ (50 ) Effective tax rate 3 % (81 )% 4 % 17 % Our income tax rates do not bear a customary relationship to statutory income tax rates primarily as a result of the effect of our NOLs, changes in unrecognized tax benefits and valuation allowances. For the three and six months ended June 30, 2019 and 2018 , our income tax expense (benefit) is largely comprised of discrete tax items and estimated state and foreign income taxes in jurisdictions where we do not have NOLs or valuation allowances. Income Tax Audits — We remain subject to periodic audits and reviews by taxing authorities; however, we do not expect these audits will have a material effect on our tax provision. Any NOLs we claim in future years to reduce taxable income could be subject to IRS examination regardless of when the NOLs were generated. Any adjustment of state or federal returns could result in a reduction of deferred tax assets rather than a cash payment of income taxes in tax jurisdictions where we have NOLs. We are currently under various state income tax audits for various periods. Our Canadian subsidiaries are currently under examination by the Canada Revenue Agency for the years ended December 31, 2013 through 2016. Valuation Allowance — U.S. GAAP requires that we consider all available evidence, both positive and negative, and tax planning strategies to determine whether, based on the weight of that evidence, a valuation allowance is needed to reduce the value of deferred tax assets. Future realization of the tax benefit of an existing deductible temporary difference or carryforward ultimately depends on the existence of sufficient taxable income of the appropriate character within the carryback or carryforward periods available under the tax law. Due to our history of losses, we were unable to assume future profits; however, we are able to consider available tax planning strategies. Limitation on Deduction of Net Business Interest Expense — On November 26, 2018, the U.S. Treasury Department released proposed regulations which would limit the current deductibility of net business interest expense. The proposed regulations would be applicable for taxable years ending after the date on which the regulations become final. Companies have the discretion to apply the proposed regulations, but must apply all such provisions of the proposed regulations on a consistent basis. As of June 30, 2019, we have not elected to apply the proposed regulations for the 2018 or 2019 tax years and we do not expect the application of the final regulations will have a material effect on our Consolidated Condensed Financial Statements. Unrecognized Tax Benefits — At June 30, 2019 , we had unrecognized tax benefits of $29 million . If recognized, $17 million of our unrecognized tax benefits could affect the annual effective tax rate and $12 million , related to deferred tax assets, could be offset against the recorded valuation allowance resulting in no effect on our effective tax rate. We had accrued interest and penalties of $3 million for income tax matters at June 30, 2019 . We recognize interest and penalties related to unrecognized tax benefits in income tax expense (benefit) on our Consolidated Condensed Statements of Operations. We believe that it is reasonably possible that a decrease within the range of nil and $8 million in unrecognized tax benefits could occur within the next twelve months primarily related to state tax issues.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Litigation We are party to various litigation matters, including regulatory and administrative proceedings arising out of the normal course of business. At the present time, we do not expect that the outcome of any of these proceedings, individually or in the aggregate, will have a material adverse effect on our financial condition, results of operations or cash flows. On a quarterly basis, we review our litigation activities and determine if an unfavorable outcome to us is considered “remote,” “reasonably possible” or “probable” as defined by U.S. GAAP. Where we determine an unfavorable outcome is probable and is reasonably estimable, we accrue for potential litigation losses. The liability we may ultimately incur with respect to such litigation matters, in the event of a negative outcome, may be in excess of amounts currently accrued, if any; however, we do not expect that the reasonably possible outcome of these litigation matters would, individually or in the aggregate, have a material adverse effect on our financial condition, results of operations or cash flows. Where we determine an unfavorable outcome is not probable or reasonably estimable, we do not accrue for any potential litigation loss. The ultimate outcome of these litigation matters cannot presently be determined, nor can the liability that could potentially result from a negative outcome be reasonably estimated. As a result, we give no assurance that such litigation matters would, individually or in the aggregate, not have a material adverse effect on our financial condition, results of operations or cash flows. Environmental Matters We are subject to complex and stringent environmental laws and regulations related to the operation of our power plants. On occasion, we may incur environmental fees, penalties and fines associated with the operation of our power plants. At the present time, we do not have environmental violations or other matters that would have a material effect on our financial condition, results of operations or cash flows or that would significantly change our operations. Guarantees and Indemnifications Our potential exposure under guarantee and indemnification obligations can range from a specified amount to an unlimited dollar amount, depending on the nature of the claim and the particular transaction. Our total maximum exposure under our guarantee and indemnification obligations is not estimable due to uncertainty as to whether claims will be made or how any potential claim will be resolved. As of June 30, 2019 , there are no material outstanding claims related to our guarantee and indemnification obligations and we do not anticipate that we will be required to make any material payments under our guarantee and indemnification obligations. There have been no material changes to our guarantees and indemnifications from those disclosed in Note 16 of our 2018 Form 10-K.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	Related Party Transactions We have entered into various agreements with related parties associated with the operation of our business. A description of these related party transactions is provided below: Calpine Receivables — Under the Accounts Receivable Sales Program, at June 30, 2019 and December 31, 2018 , we had $244 million and $238 million , respectively, in trade accounts receivable outstanding that were sold to Calpine Receivables and $57 million and $34 million , respectively, in notes receivable from Calpine Receivables which were recorded on our Consolidated Condensed Balance Sheets. During the six months ended June 30, 2019 and 2018 , we sold an aggregate of $1.1 billion and $1.1 billion , respectively, in trade accounts receivable and recorded $1.1 billion and $1.1 billion , respectively, in proceeds. For a further discussion of the Accounts Receivable Sales Program and Calpine Receivables, see Notes 7 and 17 in our 2018 Form 10-K. Lyondell — We have a ground lease agreement with Houston Refining LP (“Houston Refining”), a subsidiary of Lyondell, for our Channel Energy Center site from which we sell power, capacity and steam to Houston Refining under a PPA. We purchase refinery gas and raw water from Houston Refining under a facilities services agreement. One of the entities which obtained an ownership interest in Calpine through the Merger also has an ownership interest in Lyondell whereby they may significantly influence the management and operating policies of Lyondell. The terms of the PPA with Lyondell were negotiated prior to the Merger closing. We recorded $17 million and $19 million in Commodity revenue during the three months ended June 30, 2019 and 2018, respectively, and $37 million and $38 million in Commodity revenue during the six months ended June 30, 2019 and 2018, associated with this contract with Lyondell. We recorded $4 million and $4 million in Commodity expense during the three months ended June 30, 2019 and 2018, respectively, and $7 million and $6 million in Commodity expense during the six months ended June 30, 2019 and 2018, associated with this contract with Lyondell. At June 30, 2019 and December 31, 2018 , the related party receivable and payable associated with this contract with Lyondell were immaterial. Other — Following the Merger, we have identified other related party contracts for the sale of power, capacity and RECs which are entered into in the ordinary course of our business. Most of these contracts relate to the sale of commodities and capacity for varying tenors. The terms of most of these contracts were negotiated prior to the Merger. As of June 30, 2019 and December 31, 2018 , the related party receivables and payables associated with these transactions were immaterial.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2019
Segment Reporting [Abstract]
Segment Information	Segment Information We assess our business on a regional basis due to the effect on our financial performance of the differing characteristics of these regions, particularly with respect to competition, regulation and other factors affecting supply and demand. At June 30, 2019 , our geographic reportable segments for our wholesale business are West (including geothermal), Texas and East (including Canada) and we have a separate reportable segment for our retail business. We continue to evaluate the optimal manner in which we assess our performance including our segments and future changes may result in changes to the composition of our geographic segments. Commodity Margin is a key operational measure of profit reviewed by our chief operating decision maker to assess the performance of our segments. The tables below show financial data for our segments (including a reconciliation of our Commodity Margin to income (loss) from operations by segment) for the periods indicated (in millions): Three Months Ended June 30, 2019 Wholesale Consolidation West Texas East Retail Elimination Total Total operating revenues (1) $ 649 $ 899 $ 646 $ 1,082 $ (677 ) $ 2,599 Commodity Margin $ 251 $ 173 $ 235 $ 93 $ — $ 752 Add: Mark-to-market commodity activity, net and other (2) 58 240 94 (182 ) (10 ) 200 Less: Operating and maintenance expense 84 66 72 33 (10 ) 245 Depreciation and amortization expense 60 54 48 13 — 175 General and other administrative expense 5 15 10 4 — 34 Other operating expenses 7 1 11 — — 19 Impairment losses — — 40 — — 40 (Income) from unconsolidated subsidiaries — — (6 ) 1 — (5 ) Income (loss) from operations 153 277 154 (140 ) — 444 Interest expense 157 Gain on extinguishment of debt and other (income) expense, net 8 Income before income taxes $ 279 Three Months Ended June 30, 2018 Wholesale Consolidation West Texas East Retail Elimination Total Total operating revenues (1) $ 355 $ 993 $ 341 $ 935 $ (365 ) $ 2,259 Commodity Margin $ 241 $ 151 $ 225 $ 77 $ — $ 694 Add: Mark-to-market commodity activity, net and other (2) (23 ) 301 (7 ) (67 ) (8 ) 196 Less: Operating and maintenance expense 80 65 65 41 (9 ) 242 Depreciation and amortization expense 67 57 49 13 — 186 General and other administrative expense 5 13 8 5 — 31 Other operating expenses 8 3 8 — — 19 (Income) from unconsolidated subsidiaries — — (6 ) 1 — (5 ) Income (loss) from operations 58 314 94 (50 ) 1 417 Interest expense 157 Other (income) expense, net 62 Income before income taxes $ 198 Six Months Ended June 30, 2019 Wholesale Consolidation West Texas East Retail Elimination Total Total operating revenues (3) $ 1,331 $ 1,642 $ 1,335 $ 2,080 $ (1,190 ) $ 5,198 Commodity Margin $ 515 $ 335 $ 500 $ 181 $ — $ 1,531 Add: Mark-to-market commodity activity, net and other (4) 114 284 107 (235 ) (18 ) 252 Less: Operating and maintenance expense 165 131 139 67 (18 ) 484 Depreciation and amortization expense 133 99 91 26 — 349 General and other administrative expense 12 27 19 8 — 66 Other operating expenses 16 3 19 — — 38 Impairment losses — — 55 — — 55 (Income) from unconsolidated subsidiaries — — (12 ) 1 — (11 ) Income (loss) from operations 303 359 296 (156 ) — 802 Interest expense 306 Gain on extinguishment of debt and other (income) expense, net 27 Income before income taxes $ 469 Six Months Ended June 30, 2018 Wholesale Consolidation West Texas East Retail Elimination Total Total operating revenues (3) $ 835 $ 1,133 $ 955 $ 1,873 $ (528 ) $ 4,268 Commodity Margin $ 426 $ 317 $ 409 $ 154 $ — $ 1,306 Add: Mark-to-market commodity activity, net and other (4) (10 ) (246 ) 33 61 (15 ) (177 ) Less: Operating and maintenance expense 170 145 136 81 (15 ) 517 Depreciation and amortization expense 134 133 94 26 — 387 General and other administrative expense 21 38 23 9 — 91 Other operating expenses 22 19 15 — — 56 (Income) from unconsolidated subsidiaries — — (12 ) 1 — (11 ) Income (loss) from operations 69 (264 ) 186 98 — 89 Interest expense 308 Other (income) expense, net 69 Loss before income taxes $ (288 ) _________ (1) Includes intersegment revenues of $100 million and $70 million in the West, $348 million and $276 million in Texas, $228 million and $18 million in the East and $1 million and $1 million in Retail for the three months ended June 30, 2019 and 2018 , respectively. (2) Includes $(19) million and $(19) million of lease levelization and $18 million and $25 million of amortization expense for the three months ended June 30, 2019 and 2018 , respectively. (3) Includes intersegment revenues of $262 million and $184 million in the West, $559 million and $209 million in Texas, $365 million and $133 million in the East and $4 million and $2 million in Retail for the six months ended June 30, 2019 and 2018, respectively. (4) Includes $(35) million and $(35) million of lease levelization and $39 million and $53 million of amortization expense for the six months ended June 30, 2019 and 2018 , respectively.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Basis of interim presentation	Basis of Interim Presentation — The accompanying unaudited, interim Consolidated Condensed Financial Statements of Calpine Corporation, a Delaware corporation, and consolidated subsidiaries have been prepared pursuant to the rules and regulations of the SEC. In the opinion of management, the Consolidated Condensed Financial Statements include the normal, recurring adjustments necessary for a fair statement of the information required to be set forth therein. Certain information and note disclosures, normally included in financial statements prepared in accordance with U.S. GAAP, have been condensed or omitted from these statements pursuant to such rules and regulations and, accordingly, these financial statements should be read in conjunction with our audited Consolidated Financial Statements for the year ended December 31, 2018 , included in our 2018 Form 10-K. The results for interim periods are not indicative of the results for the entire year primarily due to acquisitions and disposals of assets, seasonal fluctuations in our revenues and expenses, timing of major maintenance expense, variations resulting from the application of the method to calculate the provision for income tax for interim periods, volatility of commodity prices and mark-to-market gains and losses from commodity and interest rate derivative contracts.
Use of estimates in preparation of financial statements	Use of Estimates in Preparation of Financial Statements — The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures included in our Consolidated Condensed Financial Statements. Actual results could differ from those estimates.
Reclassification, Policy [Policy Text Block]	Reclassifications — We have reclassified certain prior period amounts for comparative purposes. These reclassifications did not have a material effect on our financial condition, results of operations or cash flows.
Cash and cash equivalents	Cash and Cash Equivalents — We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents. We have cash and cash equivalents held in non-corporate accounts relating to certain project finance facilities and lease agreements that require us to establish and maintain segregated cash accounts. These accounts have been pledged as security in favor of the lenders under such project finance facilities, and the use of certain cash balances on deposit in such accounts is limited, at least temporarily, to the operations of the respective projects.
Restricted cash	Restricted Cash — Certain of our debt agreements, lease agreements or other operating agreements require us to establish and maintain segregated cash accounts, the use of which is restricted, making these cash funds unavailable for general use. These amounts are held by depository banks in order to comply with the contractual provisions requiring reserves for payments such as for debt service, rent and major maintenance or with applicable regulatory requirements. Funds that can be used to satisfy obligations due during the next 12 months are classified as current restricted cash, with the remainder classified as non-current restricted cash. Restricted cash is generally invested in accounts earning market rates; therefore, the carrying value approximates fair value. Such cash is excluded from cash and cash equivalents on our Consolidated Condensed Balance Sheets.
Business Interruption Proceeds [Policy Text Block]	Business Interruption Proceeds — We record business interruption insurance proceeds in operating revenues when they are realizable.
New accounting pronouncements, policy	Leases — On January 1, 2019, we adopted Accounting Standards Update 2016-02, “Leases” (“Topic 842”). The comprehensive new lease standard superseded all existing lease guidance. The standard requires that a lessee should recognize a right-of-use asset and a lease liability for substantially all operating leases based on the present value of the minimum rental payments. For lessors, the accounting for leases under Topic 842 remained substantially unchanged. The standard also requires expanded disclosures surrounding leases. We adopted the standards under Topic 842 using the modified retrospective method and elected a number of the practical expedients in our implementation of Topic 842. The key change that affected us relates to our accounting for operating leases for which we are the lessee that were historically off-balance sheet. The impact of adopting the standards resulted in the recognition of a right-of-use asset and lease obligation liability of $191 million on our Consolidated Condensed Balance Sheet on January 1, 2019, exclusive of previously recognized lease balances. The implementation of Topic 842 did not have a material effect on our Consolidated Condensed Statement of Operations or Consolidated Condensed Statement of Cash Flows for the six months ended June 30, 2019 . See Note 3 for a discussion of the practical expedients we elected and additional disclosures required by Topic 842. Derivatives and Hedging — In August 2017, the FASB issued Accounting Standards Update 2017-12, “Targeted Improvements to Accounting for Hedging Activities.” The standard better aligns an entity’s hedging activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results in the financial statements. The standard will prospectively make hedge accounting easier to apply to hedging activities and also enhances disclosure requirements for how hedge transactions are reflected in the financial statements when hedge accounting is elected. We adopted Accounting Standards Update 2017-12 in the first quarter of 2019 which did not have a material effect on our financial condition, results of operations or cash flows. Fair Value Measurements — In August 2018, the FASB issued Accounting Standards Update 2018-13, “Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement.” The standard removes, modifies and adds disclosures about fair value measurements and is effective for fiscal years beginning after December 15, 2019. The changes required by this standard to remove or modify disclosures may be early adopted with adoption of the additional disclosures required by this standard delayed until their effective date. We do not anticipate a material effect on our financial condition, results of operations or cash flows as a result of adopting this standard.
Lessee, Leases [Policy Text Block]	Accounting for Leases – Lessee We evaluate contracts for lease accounting at contract inception and assess lease classification at the lease commencement date. For our leases, we recognize a right-of-use asset and corresponding lease obligation liability at the lease commencement date where the lease obligation liability is measured at the present value of the minimum lease payments. For our operating leases, the amortization of the right-of-use asset and the accretion of our lease obligation liability result in a single straight-line expense recognized over the lease term. We determine the discount rate associated with our operating and finance leases using our incremental borrowing rate at lease commencement. For our operating leases, we use an interest rate commensurate with the interest rate to borrow on a collateralized basis over a similar term with an amount equal to the lease payments. Factors management considers in the calculation of the discount rate include the amount of the borrowing, the lease term including options that are reasonably certain of exercise, the current interest rate environment and the credit rating of the entity. For our finance leases, we use the interest rate commensurate with the interest rate for a project finance borrowing arrangement with a similar collateral package, repayment terms, restrictive covenants and guarantees. Our operating leases are primarily related to office space for our corporate and regional offices as well as land and operating related leases for our power plants. Additionally, one of our power plants is accounted for as a long-term operating lease. Payments made by Calpine on this lease are recognized on a straight-line basis with capital improvements associated with our leased power plant deemed leasehold improvements that are amortized over the shorter of the term of the lease or the economic life of the capital improvement. Several of our leases contain renewal options held by us to extend the lease term. The inclusion of these renewal periods in the lease term and in the minimum lease payments included in our lease liabilities is dependent on specific facts and circumstances for each lease and whether it is determined to be reasonably certain that we will exercise our option to extend the term. Our office, land and other operating leases do not contain any material restrictive covenants or residual value guarantees. We have entered into finance leases for certain power plants and related equipment with terms that range up to 30 years (including lease renewal options). The finance leases generally provide for the lessee to pay taxes, maintenance, insurance, and certain other operating costs of the leased property. In connection with our adoption of Topic 842 on January 1, 2019, we elected certain practical expedients that were available under the new lease standards including: • we elected not to separate lease and nonlease components for our current classes of underlying leased assets as the lessee; • we did not evaluate existing and expired land easements that were not previously accounted for as leases prior to January 1, 2019; and • we did not reassess the classification of leases, the accounting for initial direct costs or whether contractual arrangements contained a lease for all contracts that expired or commenced prior to January 1, 2019. Further, upon the adoption of Topic 842, we made an accounting policy election to not recognize lease assets and liabilities for leases with a term of 12 months or less. We do not have any material subleases associated with our operating and finance leases.
Lessor, Leases [Policy Text Block]	Accounting for Leases – Lessor We apply lease accounting to PPAs that meet the definition of a lease and determine lease classification treatment at commencement of the agreement. We currently do not have any contracts which are accounted for as sales-type leases or direct financing leases and all of our leases as the lessor are classified as operating leases. As part of the implementation of Topic 842, we elected the practical expedient to not reassess leases that have commenced prior to January 1, 2019. Revenue from contracts accounted for as operating leases, such as certain tolling agreements, with minimum lease rentals (capacity payments) which vary over time must be levelized. Generally, we levelize these contract revenues on a straight-line basis over the term of the contract. Our operating leases that have commenced contain terms extending through December 2034. These contracts also generally contain variable payment components based on generation volumes or operating efficiency over a period of time. Revenues associated with the variable payments are recognized over time as the goods or services are provided to the lessee. Our operating leases generally do not contain renewal or purchase options or residual value guarantees. We have elected to not separate our lease and non-lease components as the lease components reflect the predominant characteristics of these agreements.
Consolidation, Variable Interest Entity, Policy [Policy Text Block]	We consolidate all of our VIEs where we have determined that we are the primary beneficiary. We have a 50% partnership interest in Greenfield LP and in Whitby. Greenfield LP and Whitby are VIEs; however, we do not have the power to direct the most significant activities of these entities and therefore do not consolidate them. Greenfield LP is a limited partnership between certain subsidiaries of ours and of Mitsui & Co., Ltd., which operates the Greenfield Energy Centre, a 1,038 MW natural gas-fired, combined-cycle power plant located in Ontario, Canada. We and Mitsui & Co., Ltd. each hold a 50% interest in Greenfield LP. Whitby is a limited partnership between certain of our subsidiaries and Atlantic Packaging Ltd., which operates the Whitby facility, a 50 MW natural gas-fired, simple-cycle cogeneration power plant located in Ontario, Canada. We and Atlantic Packaging Ltd. each hold a 50% partnership interest in Whitby. Calpine Receivables is a VIE and a bankruptcy remote entity created for the special purpose of purchasing trade accounts receivable from Calpine Solutions under the Accounts Receivable Sales Program. We have determined that we do not have the power to direct the activities of the VIE that most significantly affect the VIE’s economic performance nor the obligation to absorb losses or receive benefits from the VIE. Accordingly, we have determined that we are not the primary beneficiary of Calpine Receivables because we do not have the power to affect its financial performance as the unaffiliated financial institutions that purchase the receivables from Calpine Receivables control the selection criteria of the receivables sold and appoint the servicer of the receivables which controls management of default. Thus, we do not consolidate Calpine Receivables in our Consolidated Condensed Financial Statements and use the equity method of accounting to record our net interest in Calpine Receivables. We account for these entities under the equity method of accounting and include our net equity interest in investments in unconsolidated subsidiaries on our Consolidated Condensed Balance Sheets.
Fair Value of Financial Instruments, Policy [Policy Text Block]	Our Senior Unsecured Notes, First Lien Term Loans, First Lien Notes, CCFC Term Loan and Corporate Revolving Facility are categorized as level 2 within the fair value hierarchy. Our project financing, notes payable and other debt instruments are categorized as level 3 within the fair value hierarchy. We do not have any debt instruments with fair value measurements categorized as level 1 within the fair value hierarchy. Cash Equivalents — Highly liquid investments which meet the definition of cash equivalents, primarily investments in money market accounts and other interest-bearing accounts, are included in both our cash and cash equivalents and our restricted cash on our Consolidated Condensed Balance Sheets. Certain of our money market accounts invest in U.S. Treasury securities or other obligations issued or guaranteed by the U.S. Government, its agencies or instrumentalities. We do not have any cash equivalents invested in institutional prime money market funds which require use of a floating net asset value and are subject to liquidity fees and redemption restrictions. Certain of our cash equivalents are classified within level 1 of the fair value hierarchy. Derivatives — The primary factors affecting the fair value of our derivative instruments at any point in time are the volume of open derivative positions (MMBtu, MWh and $ notional amounts); changing commodity market prices, primarily for power and natural gas; our credit standing and that of our counterparties and customers for energy commodity derivatives; and prevailing interest rates for our interest rate hedging instruments. Prices for power and natural gas and interest rates are volatile, which can result in material changes in the fair value measurements reported in our financial statements in the future. We utilize market data, such as pricing services and broker quotes, and assumptions that we believe market participants would use in pricing our assets or liabilities including assumptions about the risks inherent to the inputs in the valuation technique. These inputs can be either readily observable, market corroborated or generally unobservable. The market data obtained from broker pricing services is evaluated to determine the nature of the quotes obtained and, where accepted as a reliable quote, used to validate our assessment of fair value. We use other qualitative assessments to determine the level of activity in any given market. We primarily apply the market approach and income approach for recurring fair value measurements and utilize what we believe to be the best available information. We utilize valuation techniques that seek to maximize the use of observable inputs and minimize the use of unobservable inputs. We classify fair value balances based on the observability of those inputs. The fair value of our derivatives includes consideration of our credit standing, the credit standing of our counterparties and customers and the effect of credit enhancements, if any. We have also recorded credit reserves in the determination of fair value based on our expectation of how market participants would determine fair value. Such valuation adjustments are generally based on market evidence, if available, or our best estimate. Our level 1 fair value derivative instruments primarily consist of power and natural gas swaps, futures and options traded on the NYMEX or Intercontinental Exchange. Our level 2 fair value derivative instruments primarily consist of interest rate hedging instruments and OTC power and natural gas forwards for which market-based pricing inputs in the principal or most advantageous market are representative of executable prices for market participants. These inputs are observable at commonly quoted intervals for substantially the full term of the instruments. In certain instances, our level 2 derivative instruments may utilize models to measure fair value. These models are industry-standard models, including the Black-Scholes option-pricing model, that incorporate various assumptions, including quoted interest rates, correlation, volatility, as well as other relevant economic measures. Substantially all of these assumptions are observable in the marketplace throughout the full term of the instrument, can be derived from observable data or are supported by observable levels at which transactions are executed in the marketplace. Our level 3 fair value derivative instruments may consist of OTC power and natural gas forwards and options where pricing inputs are unobservable, as well as other complex and structured transactions primarily for the sale and purchase of power and natural gas to both wholesale counterparties and retail customers. Complex or structured transactions are tailored to our customers’ needs and can introduce the need for internally-developed model inputs which might not be observable in or corroborated by the market. When such inputs have a significant effect on the measurement of fair value, the instrument is categorized in level 3. Our valuation models may incorporate historical correlation information and extrapolate available broker and other information to future periods.
Derivatives, Policy [Policy Text Block]	We offset fair value amounts associated with our derivative instruments and related cash collateral and margin deposits on our Consolidated Condensed Balance Sheets that are executed with the same counterparty under master netting arrangements. Our netting arrangements include a right to set off or net together purchases and sales of similar products in the margining or settlement process. In some instances, we have also negotiated cross commodity netting rights which allow for the net presentation of activity with a given counterparty regardless of product purchased or sold. We also post and/or receive cash collateral in support of our derivative instruments which may also be subject to a master netting arrangement with the same counterparty. We recognize all derivative instruments that qualify for derivative accounting treatment as either assets or liabilities and measure those instruments at fair value unless they qualify for, and we elect, the normal purchase normal sale exemption. For transactions in which we elect the normal purchase normal sale exemption, gains and losses are not reflected on our Consolidated Condensed Statements of Operations until the period of delivery. Revenues and expenses derived from instruments that qualified for hedge accounting or represent an economic hedge are recorded in the same financial statement line item as the item being hedged. Hedge accounting requires us to formally document, designate and assess the effectiveness of transactions that receive hedge accounting. We present the cash flows from our derivatives in the same category as the item being hedged (or economically hedged) within operating activities on our Consolidated Condensed Statements of Cash Flows unless they contain an other-than-insignificant financing element in which case their cash flows are classified within financing activities. Cash Flow Hedges — We currently apply hedge accounting to our interest rate hedging instruments. We report the mark-to-market gain or loss on our interest rate hedging instruments designated and qualifying as a cash flow hedging instrument as a component of OCI and reclassify such gains and losses into earnings in the same period during which the hedged forecasted transaction affects earnings. Prior to January 1, 2019, gains and losses due to ineffectiveness on interest rate hedging instruments were recognized in earnings as a component of interest expense. Upon the adoption of Accounting Standards Update 2017-12 on January 1, 2019, hedge ineffectiveness is no longer separately measured and recorded in earnings. If it is determined that the forecasted transaction is no longer probable of occurring, then hedge accounting will be discontinued prospectively and future changes in fair value will be recorded in earnings. If the hedging instrument is terminated or de-designated prior to the occurrence of the hedged forecasted transaction, the net accumulated gain or loss associated with the changes in fair value of the hedge instrument remains deferred in AOCI until such time as the forecasted transaction affects earnings or until it is determined that the forecasted transaction is probable of not occurring. Derivatives Not Designated as Hedging Instruments — We enter into power, natural gas, interest rate, environmental product and fuel oil transactions that primarily act as economic hedges to our asset and interest rate portfolio, but either do not qualify as hedges under the hedge accounting guidelines or qualify under the hedge accounting guidelines and the hedge accounting designation has not been elected. Changes in fair value of commodity derivatives not designated as hedging instruments are recognized currently in earnings and are separately stated on our Consolidated Condensed Statements of Operations in mark-to-market gain/loss as a component of operating revenues (for physical and financial power and Heat Rate and commodity option activity) and fuel and purchased energy expense (for physical and financial natural gas, power, environmental product and fuel oil activity). Changes in fair value of interest rate derivatives not designated as hedging instruments are recognized currently in earnings as interest expense.
Commitments and Contingencies, Policy [Policy Text Block]	On a quarterly basis, we review our litigation activities and determine if an unfavorable outcome to us is considered “remote,” “reasonably possible” or “probable” as defined by U.S. GAAP. Where we determine an unfavorable outcome is probable and is reasonably estimable, we accrue for potential litigation losses. The liability we may ultimately incur with respect to such litigation matters, in the event of a negative outcome, may be in excess of amounts currently accrued, if any; however, we do not expect that the reasonably possible outcome of these litigation matters would, individually or in the aggregate, have a material adverse effect on our financial condition, results of operations or cash flows. Where we determine an unfavorable outcome is not probable or reasonably estimable, we do not accrue for any potential litigation loss. The ultimate outcome of these litigation matters cannot presently be determined, nor can the liability that could potentially result from a negative outcome be reasonably estimated. As a result, we give no assurance that such litigation matters would, individually or in the aggregate, not have a material adverse effect on our financial condition, results of operations or cash flows.

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Schedule of components of restricted cash	The table below represents the components of our restricted cash as of June 30, 2019 and December 31, 2018 (in millions): June 30, 2019 December 31, 2018 Current Non-Current Total Current Non-Current Total Debt service $ 51 $ 8 $ 59 $ 13 $ 8 $ 21 Construction/major maintenance 9 39 48 23 24 47 Security/project/insurance 112 31 143 120 — 120 Other 10 2 12 11 2 13 Total $ 182 $ 80 $ 262 $ 167 $ 34 $ 201
Schedule of property, plant and equipment	Property, Plant and Equipment, Net — At June 30, 2019 and December 31, 2018 , the components of property, plant and equipment are stated at cost less accumulated depreciation as follows (in millions): June 30, 2019 December 31, 2018 Depreciable Lives Buildings, machinery and equipment $ 16,522 $ 16,400 1.5 – 50 Years Geothermal properties 1,509 1,501 13 – 58 Years Other 269 286 3 – 50 Years 18,300 18,187 Less: Accumulated depreciation 6,860 6,832 11,440 11,355 Land 128 121 Construction in progress 483 966 Property, plant and equipment, net $ 12,051 $ 12,442

Revenue From Contracts with C_2

Revenue From Contracts with Customers (Tables)	6 Months Ended
	Jun. 30, 2019
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue [Table Text Block]	The following tables represent a disaggregation of our revenue for the three and six months ended June 30, 2019 and 2018 by reportable segment (in millions). See Note 13 for a description of our segments. Three Months Ended June 30, 2019 Wholesale West Texas East Retail Elimination Total Third-Party: Energy & other products $ 145 $ 318 $ 124 $ 413 $ — $ 1,000 Capacity 36 33 154 — — 223 Revenues relating to physical or executory contracts – third-party $ 181 $ 351 $ 278 $ 413 $ — $ 1,223 Affiliate (1) : $ 6 $ 14 $ 30 $ 1 $ (51 ) $ — Revenues relating to leases and derivative instruments (2) $ 1,376 Total operating revenues $ 2,599 Three Months Ended June 30, 2018 Wholesale West Texas East Retail Elimination Total Third-Party: Energy & other products $ 176 $ 326 $ 120 $ 451 $ — $ 1,073 Capacity 35 23 140 — — 198 Revenues relating to physical or executory contracts – third-party $ 211 $ 349 $ 260 $ 451 $ — $ 1,271 Affiliate (1) : $ 5 $ 9 $ 21 $ 1 $ (36 ) $ — Revenues relating to leases and derivative instruments (2) $ 988 Total operating revenues $ 2,259 Six Months Ended June 30, 2019 Wholesale West Texas East Retail Elimination Total Third-Party: Energy & other products $ 437 $ 620 $ 327 $ 825 $ — $ 2,209 Capacity 71 65 331 — — 467 Revenues relating to physical or executory contracts – third-party $ 508 $ 685 $ 658 $ 825 $ — $ 2,676 Affiliate (1) : $ 17 $ 28 $ 57 $ 4 $ (106 ) $ — Revenues relating to leases and derivative instruments (2) $ 2,522 Total operating revenues $ 5,198 Six Months Ended June 30, 2018 Wholesale West Texas East Retail Elimination Total Third-Party: Energy & other products $ 375 $ 630 $ 252 $ 894 $ — $ 2,151 Capacity 54 49 289 — — 392 Revenues relating to physical or executory contracts – third-party $ 429 $ 679 $ 541 $ 894 $ — $ 2,543 Affiliate (1) : $ 13 $ 13 $ 42 $ 2 $ (70 ) $ — Revenues relating to leases and derivative instruments (2) $ 1,725 Total operating revenues $ 4,268 ___________ (1) Affiliate energy, other and capacity revenues reflect revenues on transactions between wholesale and retail affiliates excluding affiliate activity related to leases and derivative instruments. All such activity supports retail supply needs from the wholesale business and/or allows for collateral margin netting efficiencies at Calpine. (2) Revenues relating to contracts accounted for as leases and derivatives include energy and capacity revenues relating to PPAs that we are required to account for as operating leases and physical and financial commodity derivative contracts, primarily relating to power, natural gas and environmental products. Revenue related to derivative instruments includes revenue recorded in Commodity revenue and mark-to-market gain (loss) within our operating revenues on our Consolidated Condensed Statements of Operations.

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Lease, Cost [Table Text Block]	The components of our operating and finance lease expense are as follows for the three and six months ended June 30, 2019 (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2019 Operating Leases Operating lease expense $ 12 $ 23 Finance Leases Amortization of the right-of-use assets $ 1 $ 4 Interest expense 2 4 Finance lease expense $ 3 $ 8 Variable lease expense $ 4 $ 5 Total lease expense $ 19 $ 36
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	The following is a schedule by year of future minimum lease payments associated with our operating and finance leases together with the present value of the net minimum lease payments as of June 30, 2019 (in millions): Operating Leases (1)(2) Finance Leases (2)(3) 2019 $ 39 $ 8 2020 20 16 2021 21 16 2022 19 16 2023 18 19 Thereafter 201 33 Total minimum lease payments 318 108 Less: Amount representing interest 108 30 Total lease obligation 210 78 Less: current lease obligation 39 10 Long-term lease obligation $ 171 $ 68 ____________ (1) The lease liabilities associated with our operating leases as of June 30, 2019 are included in other current liabilities and other long-term liabilities on our Consolidated Condensed Balance Sheet. (2) Excludes an operating lease obligation of $1 million and a finance lease obligation of $18 million related to Garrison Energy Center which are included in current liabilities held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center. (3) The lease liabilities associated with our finance leases as of June 30, 2019 are included in debt, current portion and debt, net of current portion on our Consolidated Condensed Balance Sheet.
Finance Lease, Liability, Maturity [Table Text Block]	The following is a schedule by year of future minimum lease payments associated with our operating and finance leases together with the present value of the net minimum lease payments as of June 30, 2019 (in millions): Operating Leases (1)(2) Finance Leases (2)(3) 2019 $ 39 $ 8 2020 20 16 2021 21 16 2022 19 16 2023 18 19 Thereafter 201 33 Total minimum lease payments 318 108 Less: Amount representing interest 108 30 Total lease obligation 210 78 Less: current lease obligation 39 10 Long-term lease obligation $ 171 $ 68 ____________ (1) The lease liabilities associated with our operating leases as of June 30, 2019 are included in other current liabilities and other long-term liabilities on our Consolidated Condensed Balance Sheet. (2) Excludes an operating lease obligation of $1 million and a finance lease obligation of $18 million related to Garrison Energy Center which are included in current liabilities held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center. (3) The lease liabilities associated with our finance leases as of June 30, 2019 are included in debt, current portion and debt, net of current portion on our Consolidated Condensed Balance Sheet.
Supplemental Balance Sheet Info Lessee [Table Text Block]	Supplemental balance sheet information related to our operating and finance leases is as follows as of June 30, 2019 (in millions, except lease term and discount rate): June 30, 2019 (1) Operating leases (2) Right-of-use assets associated with operating leases $ 184 Finance leases (3) Property, plant and equipment, gross $ 213 Accumulated amortization (104 ) Property, plant and equipment, net $ 109 Weighted average remaining lease term (in years) Operating leases 15.8 Finance leases 7.4 Weighted average discount rate Operating leases 5.1 % Finance leases 8.0 % ____________ (1) Excludes a right-of-use asset and property, plant and equipment, net of $1 million and $17 million , respectively, related to Garrison Energy Center which are included in current assets held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center. (2) The right-of-use assets associated with our operating leases as of June 30, 2019 are included in other assets on our Consolidated Condensed Balance Sheet. (3) The right-of-use assets associated with our finance leases as of June 30, 2019 are included in property, plant and equipment, net on our Consolidated Condensed Balance Sheet.
Supplemental Cash Flow Lessee [Table Text Block]	Supplemental cash flow information related to our operating and finance leases is as follows for the period presented (in millions): Six Month Ended June 30, 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 13 Operating cash flows from finance leases $ 4 Financing cash flows from finance leases $ 6 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 9 Finance leases $ —
Lease Cost - Lessor [Table Text Block]	Revenue recognized related to fixed lease payments on our operating leases for the period presented is as follows (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2019 Operating Leases (1) Fixed lease payments $ 70 $ 139 ____________ (1) Revenues associated with our operating leases are included in Commodity revenue and other revenue on our Consolidated Condensed Statement of Operations. June 30, 2019 Assets subject to contracts accounted for as operating leases Property, plant and equipment, gross $ 3,076 Accumulated depreciation (903 ) Property, plant and equipment, net (1) $ 2,173 ____________ (1) Our assets subject to contracts that are accounted for as operating leases primarily consist of our power plants subject to tolling contracts.
Lessor, Operating Lease, Payments to be Received, Maturity [Table Text Block]	The total contractual future minimum lease rentals for our contracts that have commenced and are accounted for as operating leases at June 30, 2019 , are as follows (in millions): 2019 $ 204 2020 287 2021 261 2022 227 2023 144 Thereafter 284 Total $ 1,407
Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]	The following is a schedule by year of future minimum lease payments under operating and capital leases as of December 31, 2018 (in millions): Operating Leases Capital Leases (1) 2019 $ 50 $ 40 2020 19 40 2021 20 38 2022 18 33 2023 17 27 Thereafter 192 92 Total minimum lease payments $ 316 270 Less: Amount representing interest 89 Present value of net minimum lease payments $ 181 ____________ (1) Includes a failed sale-leaseback transaction related to our Pasadena Power Plant.
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	The total contractual future minimum lease rentals for our contracts accounted for as operating leases at December 31, 2018 , are as follows (in millions): 2019 $ 342 2020 261 2021 257 2022 224 2023 141 Thereafter 239 Total $ 1,464 The following is a schedule by year of future minimum lease payments under operating and capital leases as of December 31, 2018 (in millions): Operating Leases Capital Leases (1) 2019 $ 50 $ 40 2020 19 40 2021 20 38 2022 18 33 2023 17 27 Thereafter 192 92 Total minimum lease payments $ 316 270 Less: Amount representing interest 89 Present value of net minimum lease payments $ 181 ____________ (1) Includes a failed sale-leaseback transaction related to our Pasadena Power Plant.

Variable Interest Entities an_2

Variable Interest Entities and Unconsolidated Investments in Power Plants (Tables)	6 Months Ended
	Jun. 30, 2019
Variable Interest Entities and Unconsolidated Investments [Abstract]
Schedule of equity method investments	At June 30, 2019 and December 31, 2018 , our equity method investments included on our Consolidated Condensed Balance Sheets were comprised of the following (in millions): Ownership Interest as of June 30, 2019 June 30, 2019 December 31, 2018 Greenfield LP (1) 50% $ 56 $ 55 Whitby 50% 10 15 Calpine Receivables 100% 5 6 Total investments in unconsolidated subsidiaries $ 71 $ 76 ____________ (1) Includes our share of accumulated other comprehensive income/loss related to interest rate hedging instruments associated with our unconsolidated subsidiary Greenfield LP’s debt.
Income (loss) from unconsolidated investments in power plants	The following table sets forth details of our (income) from unconsolidated subsidiaries for the periods indicated (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Greenfield LP $ (4 ) $ (2 ) $ (6 ) $ (4 ) Whitby (2 ) (4 ) (6 ) (8 ) Calpine Receivables 1 1 1 1 Total $ (5 ) $ (5 ) $ (11 ) $ (11 )

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Schedule of long-term debt instruments	Our debt at June 30, 2019 and December 31, 2018 , was as follows (in millions): June 30, 2019 December 31, 2018 Senior Unsecured Notes $ 2,990 $ 3,036 First Lien Term Loans 2,979 2,976 First Lien Notes 2,402 2,400 Project financing, notes payable and other 1,229 1,264 CCFC Term Loan 971 974 Finance lease obligations 78 105 Corporate Revolving Facility 75 30 Subtotal 10,724 10,785 Less: Current maturities 263 637 Total long-term debt $ 10,461 $ 10,148
Senior Unsecured Notes	The amounts outstanding under our Senior Unsecured Notes are summarized in the table below (in millions): June 30, 2019 December 31, 2018 2023 Senior Unsecured Notes $ 1,228 $ 1,227 2024 Senior Unsecured Notes 589 599 2025 Senior Unsecured Notes 1,173 1,210 Total Senior Unsecured Notes $ 2,990 $ 3,036
First Lien Term Loans	The amounts outstanding under our senior secured First Lien Term Loans are summarized in the table below (in millions): June 30, 2019 December 31, 2018 2019 First Lien Term Loan $ — $ 389 2023 First Lien Term Loans 535 1,059 2024 First Lien Term Loan 1,522 1,528 2026 First Lien Term Loan 922 — Total First Lien Term Loans $ 2,979 $ 2,976
First Lien Notes	The amounts outstanding under our senior secured First Lien Notes are summarized in the table below (in millions): June 30, 2019 December 31, 2018 2022 First Lien Notes $ 744 $ 743 2024 First Lien Notes 487 486 2026 First Lien Notes 1,171 1,171 Total First Lien Notes $ 2,402 $ 2,400
Schedule of line of credit facilities	The table below represents amounts issued under our letter of credit facilities at June 30, 2019 and December 31, 2018 (in millions): June 30, 2019 December 31, 2018 Corporate Revolving Facility (1) $ 585 $ 693 CDHI (2) 30 251 Various project financing facilities 227 228 Other corporate facilities (3) 293 193 Total $ 1,135 $ 1,365 ____________ (1) The Corporate Revolving Facility represents our primary revolving facility. On April 5, 2019, we amended our Corporate Revolving Facility to increase the capacity by approximately $330 million from $1.69 billion to approximately $2.02 billion . (2) Pursuant to the terms and conditions of the CDHI credit agreement, the capacity under the CDHI letter of credit facility was reduced to $125 million on June 28, 2019. The decrease in capacity did not have a material effect on our liquidity as alternative sources of liquidity are available. (3) We have three unsecured letter of credit facilities with two third-party financial institutions totaling approximately $300 million at June 30, 2019 .
Schedule of carrying values and estimated fair values of debt instruments	The following table details the fair values and carrying values of our debt instruments at June 30, 2019 and December 31, 2018 (in millions): June 30, 2019 December 31, 2018 Fair Value Carrying Value Fair Value Carrying Value Senior Unsecured Notes $ 3,011 $ 2,990 $ 2,803 $ 3,036 First Lien Term Loans 3,013 2,979 2,877 2,976 First Lien Notes 2,462 2,402 2,299 2,400 Project financing, notes payable and other (1) 1,136 1,153 1,209 1,188 CCFC Term Loan 980 971 938 974 Corporate Revolving Facility 75 75 30 30 Total $ 10,677 $ 10,570 $ 10,156 $ 10,604 ____________ (1) Excludes an agreement that is accounted for as a failed sale-leaseback transaction under U.S. GAAP.

Assets and Liabilities with R_2

Assets and Liabilities with Recurring Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value, Measurement Inputs, Disclosure	The following tables present our financial assets and liabilities that were accounted for at fair value on a recurring basis as of June 30, 2019 and December 31, 2018 , by level within the fair value hierarchy: Assets and Liabilities with Recurring Fair Value Measures as of June 30, 2019 Level 1 Level 2 Level 3 Total (in millions) Assets: Cash equivalents (1) $ 165 $ — $ — $ 165 Commodity instruments: Commodity exchange traded derivatives contracts 1,089 — — 1,089 Commodity forward contracts (2) — 350 322 672 Interest rate hedging instruments — 6 — 6 Effect of netting and allocation of collateral (3)(4) (1,089 ) (243 ) (20 ) (1,352 ) Total assets $ 165 $ 113 $ 302 $ 580 Liabilities: Commodity instruments: Commodity exchange traded derivatives contracts $ 1,179 $ — $ — $ 1,179 Commodity forward contracts (2) — 474 96 570 Interest rate hedging instruments — 33 — 33 Effect of netting and allocation of collateral (3)(4) (1,179 ) (298 ) (21 ) (1,498 ) Total liabilities $ — $ 209 $ 75 $ 284 Assets and Liabilities with Recurring Fair Value Measures as of December 31, 2018 Level 1 Level 2 Level 3 Total (in millions) Assets: Cash equivalents (1) $ 168 $ — $ — $ 168 Commodity instruments: Commodity exchange traded derivatives contracts 933 — — 933 Commodity forward contracts (2) — 338 212 550 Interest rate hedging instruments — 40 — 40 Effect of netting and allocation of collateral (3)(4) (933 ) (262 ) (26 ) (1,221 ) Total assets $ 168 $ 116 $ 186 $ 470 Liabilities: Commodity instruments: Commodity exchange traded derivatives contracts $ 932 $ — $ — $ 932 Commodity forward contracts (2) — 549 220 769 Interest rate hedging instruments — 10 — 10 Effect of netting and allocation of collateral (3)(4) (932 ) (310 ) (26 ) (1,268 ) Total liabilities $ — $ 249 $ 194 $ 443 ___________ (1) At June 30, 2019 and December 31, 2018 , we had cash equivalents of $16 million and $23 million included in cash and cash equivalents and $149 million and $145 million included in restricted cash, respectively. (2) Includes OTC swaps and options. (3) We offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation; therefore, amounts recognized for the right to reclaim, or the obligation to return, cash collateral are presented net with the corresponding derivative instrument fair values. See Note 8 for further discussion of our derivative instruments subject to master netting arrangements. (4) Cash collateral posted with (received from) counterparties allocated to level 1, level 2 and level 3 derivative instruments totaled $90 million , $55 million and $1 million , respectively, at June 30, 2019 . Cash collateral posted with (received from) counterparties allocated to level 1, level 2 and level 3 derivative instruments totaled $(1) million , $48 million and nil , respectively, at December 31, 2018 .
Fair Value Inputs, Assets, Quantitative Information	The following table presents quantitative information for the unobservable inputs used in our most significant level 3 fair value measurements at June 30, 2019 and December 31, 2018 : Quantitative Information about Level 3 Fair Value Measurements June 30, 2019 Fair Value, Net Asset Significant Unobservable (Liability) Valuation Technique Input Range (in millions) Power Contracts (1) $ 190 Discounted cash flow Market price (per MWh) $ 7.09 — $123.34 /MWh Power Congestion Products $ 18 Discounted cash flow Market price (per MWh) $ (8.63 ) — $11.48 /MWh Natural Gas Contracts $ 6 Discounted cash flow Market price (per MMBtu) $ 0.61 — $9.75 /MMBtu December 31, 2018 Fair Value, Net Asset Significant Unobservable (Liability) Valuation Technique Input Range (in millions) Power Contracts (1) $ 36 Discounted cash flow Market price (per MWh) $ 2.12 — $227.98 /MWh Power Congestion Products $ 26 Discounted cash flow Market price (per MWh) $ (11.71 ) — $11.88 /MWh Natural Gas Contracts $ (73 ) Discounted cash flow Market price (per MMBtu) $ 0.75 — $8.87 /MMBtu ___________ (1) Power contracts include power and heat rate instruments classified as level 3 in the fair value hierarchy.
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	The following table sets forth a reconciliation of changes in the fair value of our net derivative assets (liabilities) classified as level 3 in the fair value hierarchy for the periods indicated (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Balance, beginning of period $ 105 $ 129 $ (8 ) $ 197 Realized and mark-to-market gains (losses): Included in net income (loss): Included in operating revenues (1) 152 31 197 (28 ) Included in fuel and purchased energy expense (2) 1 18 2 15 Change in collateral (1 ) 1 1 (1 ) Purchases, Issuances and settlements: Purchases 1 5 3 9 Issuances (1 ) — (1 ) — Settlements (35 ) (42 ) 28 (53 ) Transfers in and/or out of level 3 (3) : Transfers into level 3 (4) 6 (1 ) 7 (1 ) Transfers out of level 3 (5) (1 ) (10 ) (2 ) (7 ) Balance, end of period $ 227 $ 131 $ 227 $ 131 Change in unrealized gains (losses) relating to instruments still held at end of period $ 153 $ 49 $ 199 $ (13 ) ___________ (1) For power contracts and other power-related products, included on our Consolidated Condensed Statements of Operations. (2) For natural gas and power contracts, swaps and options, included on our Consolidated Condensed Statements of Operations. (3) We transfer amounts among levels of the fair value hierarchy as of the end of each period. There were no transfers into or out of level 1 for each of the three and six months ended June 30, 2019 and 2018 . (4) We had $6 million in gains and $(1) million in losses transferred out of level 2 into level 3 for the three months ended June 30, 2019 and 2018 , respectively, and $7 million in gains and $(1) million in losses transferred out of level 2 into level 3 for the six months ended June 30, 2019 and 2018 , respectively, due to changes in market liquidity in various power markets. (5) We had $1 million and $10 million in gains transferred out of level 3 into level 2 for the three months ended June 30, 2019 and 2018 , respectively, and $2 million and $7 million in gains transferred out of level 3 into level 2 for the six months ended June 30, 2019 and 2018 , respectively, due to changes in market liquidity in various power markets.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts of Outstanding Derivative Positions	As of June 30, 2019 and December 31, 2018 , the net forward notional buy (sell) position of our outstanding commodity derivative instruments that did not qualify or were not designated under the normal purchase normal sale exemption and our interest rate hedging instruments were as follows: Derivative Instruments Notional Amounts June 30, 2019 December 31, 2018 Unit of Measure Power (181 ) (161 ) Million MWh Natural gas 1,048 1,045 Million MMBtu Environmental credits 13 13 Million Tonnes Interest rate hedging instruments $ 4.3 $ 4.5 Billion U.S. dollars
Derivative Instruments Subject to Master Netting Arrangements [Table Text Block]	The following tables present the fair values of our derivative instruments and our net exposure after offsetting amounts subject to a master netting arrangement with the same counterparty to our derivative instruments recorded on our Consolidated Condensed Balance Sheets by location and hedge type at June 30, 2019 and December 31, 2018 (in millions): June 30, 2019 Gross Amounts of Assets and (Liabilities) Gross Amounts Offset on the Consolidated Condensed Balance Sheets Net Amount Presented on the Consolidated Condensed Balance Sheets (1) Derivative assets: Commodity exchange traded derivatives contracts $ 861 $ (861 ) $ — Commodity forward contracts 388 (188 ) 200 Interest rate hedging instruments 5 (3 ) 2 Total current derivative assets (2) $ 1,254 $ (1,052 ) $ 202 Commodity exchange traded derivatives contracts 228 (228 ) — Commodity forward contracts 284 (71 ) 213 Interest rate hedging instruments 1 (1 ) — Total long-term derivative assets (2) $ 513 $ (300 ) $ 213 Total derivative assets $ 1,767 $ (1,352 ) $ 415 Derivative (liabilities): Commodity exchange traded derivatives contracts $ (861 ) $ 861 $ — Commodity forward contracts (393 ) 234 (159 ) Interest rate hedging instruments (9 ) 3 (6 ) Total current derivative (liabilities) (2) $ (1,263 ) $ 1,098 $ (165 ) Commodity exchange traded derivatives contracts (318 ) 318 — Commodity forward contracts (177 ) 81 (96 ) Interest rate hedging instruments (24 ) 1 (23 ) Total long-term derivative (liabilities) (2) $ (519 ) $ 400 $ (119 ) Total derivative liabilities $ (1,782 ) $ 1,498 $ (284 ) Net derivative assets (liabilities) $ (15 ) $ 146 $ 131 December 31, 2018 Gross Amounts of Assets and (Liabilities) Gross Amounts Offset on the Consolidated Condensed Balance Sheets Net Amount Presented on the Consolidated Condensed Balance Sheets (1) Derivative assets: Commodity exchange traded derivatives contracts $ 820 $ (820 ) $ — Commodity forward contracts 341 (229 ) 112 Interest rate hedging instruments 30 — 30 Total current derivative assets (3) $ 1,191 $ (1,049 ) $ 142 Commodity exchange traded derivatives contracts 113 (113 ) — Commodity forward contracts 209 (59 ) 150 Interest rate hedging instruments 10 — 10 Total long-term derivative assets (3) $ 332 $ (172 ) $ 160 Total derivative assets $ 1,523 $ (1,221 ) $ 302 Derivative (liabilities): Commodity exchange traded derivatives contracts $ (764 ) $ 764 $ — Commodity forward contracts (576 ) 277 (299 ) Interest rate hedging instruments (4 ) — (4 ) Total current derivative (liabilities) (3) $ (1,344 ) $ 1,041 $ (303 ) Commodity exchange traded derivatives contracts (168 ) 168 — Commodity forward contracts (193 ) 59 (134 ) Interest rate hedging instruments (6 ) — (6 ) Total long-term derivative (liabilities) (3) $ (367 ) $ 227 $ (140 ) Total derivative liabilities $ (1,711 ) $ 1,268 $ (443 ) Net derivative assets (liabilities) $ (188 ) $ 47 $ (141 ) ____________ (1) At June 30, 2019 and December 31, 2018 , we had $142 million and $244 million , respectively, of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets primarily related to initial margin requirements. (2) At June 30, 2019 , current and long-term derivative assets are shown net of collateral of $(27) million and $(3) million , respectively, and current and long-term derivative liabilities are shown net of collateral of $72 million and $104 million , respectively. (3) At December 31, 2018 , current and long-term derivative assets are shown net of collateral of $(58) million and $(8) million , respectively, and current and long-term derivative liabilities are shown net of collateral of $49 million and $64 million , respectively.
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	June 30, 2019 December 31, 2018 Fair Value of Derivative Assets Fair Value of Derivative Liabilities Fair Value of Derivative Assets Fair Value of Derivative Liabilities Derivatives designated as cash flow hedging instruments: Interest rate hedging instruments $ 2 $ 27 $ 40 $ 10 Total derivatives designated as cash flow hedging instruments $ 2 $ 27 $ 40 $ 10 Derivatives not designated as hedging instruments: Commodity instruments $ 413 $ 255 $ 262 $ 433 Interest rate hedging instruments — 2 — — Total derivatives not designated as hedging instruments $ 413 $ 257 $ 262 $ 433 Total derivatives $ 415 $ 284 $ 302 $ 443
Realized Unrealized Gain Loss by Instrument	The following tables detail the components of our total activity for both the net realized gain (loss) and the net mark-to-market gain (loss) recognized from our derivative instruments in earnings and where these components were recorded on our Consolidated Condensed Statements of Operations for the periods indicated (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Realized gain (loss) (1)(2) Commodity derivative instruments $ 58 $ 69 $ 169 $ 66 Total realized gain (loss) $ 58 $ 69 $ 169 $ 66 Mark-to-market gain (loss) (3) Commodity derivative instruments $ 187 $ 188 $ 233 $ (183 ) Interest rate hedging instruments (1 ) 1 (2 ) 3 Total mark-to-market gain (loss) $ 186 $ 189 $ 231 $ (180 ) Total activity, net $ 244 $ 258 $ 400 $ (114 ) ___________ (1) Does not include the realized value associated with derivative instruments that settle through physical delivery. (2) Includes amortization of acquisition date fair value of financial derivative activity related to the acquisition of Champion Energy and Calpine Solutions. (3) In addition to changes in market value on derivatives not designated as hedges, changes in mark-to-market gain (loss) also includes adjustments to reflect changes in credit default risk exposure.
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location	Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Realized and mark-to-market gain (loss) (1) Derivatives contracts included in operating revenues (2)(3) $ 541 $ 183 $ 578 $ (176 ) Derivatives contracts included in fuel and purchased energy expense (2)(3) (296 ) 74 (176 ) 59 Interest rate hedging instruments included in interest expense (1 ) 1 (2 ) 3 Total activity, net $ 244 $ 258 $ 400 $ (114 ) ___________ (1) In addition to changes in market value on derivatives not designated as hedges, changes in mark-to-market gain (loss) also includes adjustments to reflect changes in credit default risk exposure. (2) Does not include the realized value associated with derivative instruments that settle through physical delivery. (3) Includes amortization of acquisition date fair value of financial derivative activity related to the acquisition of Champion Energy and Calpine Solutions.
Derivatives Designated as Hedges	The following table details the effect of our net derivative instruments that qualified for hedge accounting treatment and are included in OCI and AOCI for the periods indicated (in millions): Three Months Ended June 30, Three Months Ended June 30, Gain (Loss) Recognized in OCI Gain (Loss) Reclassified from AOCI into Income (3)(4) 2019 2018 2019 2018 Affected Line Item on the Consolidated Condensed Statements of Operations Interest rate hedging instruments (1)(2) $ (32 ) $ 15 $ 3 $ — Interest expense Total $ (32 ) $ 15 $ 3 $ — Six Months Ended June 30, Six Months Ended June 30, Gain (Loss) Recognized in OCI Gain (Loss) Reclassified from AOCI into Income (3)(4) 2019 2018 2019 2018 Affected Line Item on the Consolidated Condensed Statements of Operations Interest rate hedging instruments (1)(2) $ (57 ) $ 69 $ 5 $ (6 ) Interest expense Interest rate hedging instruments (1)(2) — 1 — (1 ) Depreciation and amortization expense Total $ (57 ) $ 70 $ 5 $ (7 ) ____________ (1) We recorded $1 million in gains on hedge ineffectiveness related to our interest rate hedging instruments designated as cash flow hedges during each of the three and six months ended June 30, 2018 . Upon the adoption of Accounting Standards Update 2017-12 on January 1, 2019, hedge ineffectiveness is no longer separately measured and recorded in earnings. (2) We recorded an income tax benefit of $1 million and $7 million for the three months ended June 30, 2019 and 2018 , respectively, and income tax benefit of $1 million and income tax expense of $4 million for the six months ended June 30, 2019 and 2018 , respectively, in AOCI related to our cash flow hedging activities. (3) Cumulative cash flow hedge losses attributable to Calpine, net of tax, remaining in AOCI were $89 million and $34 million at June 30, 2019 and December 31, 2018 , respectively. Cumulative cash flow hedge losses attributable to the noncontrolling interest, net of tax, remaining in AOCI were $4 million and $3 million at June 30, 2019 and December 31, 2018 , respectively. (4) Includes losses (gains) of nil that were reclassified from AOCI to interest expense for the three months ended June 30, 2019 and 2018 , and losses of $1 million and nil that were reclassified from AOCI to interest expense for the six months ended June 30, 2019 and 2018 , respectively, where the hedged transactions became probable of not occurring.

Use of Collateral (Tables)

Use of Collateral (Tables)	6 Months Ended
	Jun. 30, 2019
Use of Collateral [Abstract]
Schedule of Collateral	The table below summarizes the balances outstanding under margin deposits, natural gas and power prepayments, and exposure under letters of credit and first priority liens for commodity procurement and risk management activities as of June 30, 2019 and December 31, 2018 (in millions): June 30, 2019 December 31, 2018 Margin deposits (1) $ 373 $ 343 Natural gas and power prepayments 34 31 Total margin deposits and natural gas and power prepayments with our counterparties (2) $ 407 $ 374 Letters of credit issued $ 900 $ 1,166 First priority liens under power and natural gas agreements 42 92 First priority liens under interest rate hedging instruments 29 10 Total letters of credit and first priority liens with our counterparties $ 971 $ 1,268 Margin deposits posted with us by our counterparties (1)(3) $ 85 $ 52 Letters of credit posted with us by our counterparties 31 27 Total margin deposits and letters of credit posted with us by our counterparties $ 116 $ 79 ___________ (1) We offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation; therefore, amounts recognized for the right to reclaim, or the obligation to return, cash collateral are presented net with the corresponding derivative instrument fair values. See Note 8 for further discussion of our derivative instruments subject to master netting arrangements. (2) At June 30, 2019 and December 31, 2018 , $162 million and $79 million , respectively, were included in current and long-term derivative assets and liabilities, $237 million and $286 million , respectively, were included in margin deposits and other prepaid expense and $8 million and $9 million , respectively, were included in other assets on our Consolidated Condensed Balance Sheets. (3) At June 30, 2019 and December 31, 2018 , $16 million and $32 million , respectively, were included in current and long-term derivative assets and liabilities, $28 million and $20 million , respectively, were included in other current liabilities and $41 million and nil , respectively, were included in other long-term liabilities on our Consolidated Condensed Balance Sheets.

Income Taxes Income Taxes (Tabl

Income Taxes Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The table below shows our consolidated income tax expense (benefit) and our effective tax rates for the periods indicated (in millions): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Income tax expense (benefit) $ 9 $ (158 ) $ 19 $ (50 ) Effective tax rate 3 % (81 )% 4 % 17 %

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2019
Segment Reporting [Abstract]
Schedule of Financial Data for Segments	The tables below show financial data for our segments (including a reconciliation of our Commodity Margin to income (loss) from operations by segment) for the periods indicated (in millions): Three Months Ended June 30, 2019 Wholesale Consolidation West Texas East Retail Elimination Total Total operating revenues (1) $ 649 $ 899 $ 646 $ 1,082 $ (677 ) $ 2,599 Commodity Margin $ 251 $ 173 $ 235 $ 93 $ — $ 752 Add: Mark-to-market commodity activity, net and other (2) 58 240 94 (182 ) (10 ) 200 Less: Operating and maintenance expense 84 66 72 33 (10 ) 245 Depreciation and amortization expense 60 54 48 13 — 175 General and other administrative expense 5 15 10 4 — 34 Other operating expenses 7 1 11 — — 19 Impairment losses — — 40 — — 40 (Income) from unconsolidated subsidiaries — — (6 ) 1 — (5 ) Income (loss) from operations 153 277 154 (140 ) — 444 Interest expense 157 Gain on extinguishment of debt and other (income) expense, net 8 Income before income taxes $ 279 Three Months Ended June 30, 2018 Wholesale Consolidation West Texas East Retail Elimination Total Total operating revenues (1) $ 355 $ 993 $ 341 $ 935 $ (365 ) $ 2,259 Commodity Margin $ 241 $ 151 $ 225 $ 77 $ — $ 694 Add: Mark-to-market commodity activity, net and other (2) (23 ) 301 (7 ) (67 ) (8 ) 196 Less: Operating and maintenance expense 80 65 65 41 (9 ) 242 Depreciation and amortization expense 67 57 49 13 — 186 General and other administrative expense 5 13 8 5 — 31 Other operating expenses 8 3 8 — — 19 (Income) from unconsolidated subsidiaries — — (6 ) 1 — (5 ) Income (loss) from operations 58 314 94 (50 ) 1 417 Interest expense 157 Other (income) expense, net 62 Income before income taxes $ 198 Six Months Ended June 30, 2019 Wholesale Consolidation West Texas East Retail Elimination Total Total operating revenues (3) $ 1,331 $ 1,642 $ 1,335 $ 2,080 $ (1,190 ) $ 5,198 Commodity Margin $ 515 $ 335 $ 500 $ 181 $ — $ 1,531 Add: Mark-to-market commodity activity, net and other (4) 114 284 107 (235 ) (18 ) 252 Less: Operating and maintenance expense 165 131 139 67 (18 ) 484 Depreciation and amortization expense 133 99 91 26 — 349 General and other administrative expense 12 27 19 8 — 66 Other operating expenses 16 3 19 — — 38 Impairment losses — — 55 — — 55 (Income) from unconsolidated subsidiaries — — (12 ) 1 — (11 ) Income (loss) from operations 303 359 296 (156 ) — 802 Interest expense 306 Gain on extinguishment of debt and other (income) expense, net 27 Income before income taxes $ 469 Six Months Ended June 30, 2018 Wholesale Consolidation West Texas East Retail Elimination Total Total operating revenues (3) $ 835 $ 1,133 $ 955 $ 1,873 $ (528 ) $ 4,268 Commodity Margin $ 426 $ 317 $ 409 $ 154 $ — $ 1,306 Add: Mark-to-market commodity activity, net and other (4) (10 ) (246 ) 33 61 (15 ) (177 ) Less: Operating and maintenance expense 170 145 136 81 (15 ) 517 Depreciation and amortization expense 134 133 94 26 — 387 General and other administrative expense 21 38 23 9 — 91 Other operating expenses 22 19 15 — — 56 (Income) from unconsolidated subsidiaries — — (12 ) 1 — (11 ) Income (loss) from operations 69 (264 ) 186 98 — 89 Interest expense 308 Other (income) expense, net 69 Loss before income taxes $ (288 ) _________ (1) Includes intersegment revenues of $100 million and $70 million in the West, $348 million and $276 million in Texas, $228 million and $18 million in the East and $1 million and $1 million in Retail for the three months ended June 30, 2019 and 2018 , respectively. (2) Includes $(19) million and $(19) million of lease levelization and $18 million and $25 million of amortization expense for the three months ended June 30, 2019 and 2018 , respectively. (3) Includes intersegment revenues of $262 million and $184 million in the West, $559 million and $209 million in Texas, $365 million and $133 million in the East and $4 million and $2 million in Retail for the six months ended June 30, 2019 and 2018, respectively. (4) Includes $(35) million and $(35) million of lease levelization and $39 million and $53 million of amortization expense for the six months ended June 30, 2019 and 2018 , respectively.

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2019	Dec. 31, 2018
Accounting Policies [Line Items]
Gain on Business Interruption Insurance Recovery		$ 0	$ 14	$ 0	$ 14
Operating Lease, Right-of-Use Asset	[1],[2]	184		184
Interest costs capitalized		1	$ 7	8	$ 14
Current		182		182			$ 167
Non-current		80		80			34
Total		262		262			201
Debt service
Accounting Policies [Line Items]
Current		51		51			13
Non-current		8		8			8
Total		59		59			21
Construction major maintenance
Accounting Policies [Line Items]
Current		9		9			23
Non-current		39		39			24
Total		48		48			47
Security project insurance
Accounting Policies [Line Items]
Current		112		112			120
Non-current		31		31			0
Total		143		143			120
Other
Accounting Policies [Line Items]
Current		10		10			11
Non-current		2		2			2
Total		$ 12		$ 12			$ 13
Accounting Standards Update 2016-02 [Member]
Accounting Policies [Line Items]
Operating Lease, Right-of-Use Asset						$ 191
[1]	Excludes a right-of-use asset and property, plant and equipment, net of $1 million and $17 million, respectively, related to Garrison Energy Center which are included in current assets held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center.
[2]	The right-of-use assets associated with our operating leases as of June 30, 2019 are included in other assets on our Consolidated Condensed Balance Sheet.

Basis of Presentation and Sum_5

Basis of Presentation and Summary of Significant Accounting Policies Property, Plant and Equipment, Net (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Buildings, machinery and equipment	$ 16,522	$ 16,400
Geothermal properties	1,509	1,501
Other	269	286
Property, plant and equipment, gross	18,300	18,187
Less: Accumulated depreciation	6,860	6,832
Property, plant and equipment, gross, less accumulated depreciation, depletion and amortization	11,440	11,355
Land	128	121
Construction in progress	483	966
Property, plant and equipment, net	$ 12,051	$ 12,442
Minimum [Member] | Building, Machinery and Equipment, Gross [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful lives	1 year 6 months
Minimum [Member] | Geothermal Properties, Gross [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful lives	13 years
Minimum [Member] | Property, Plant and Equipment, Other Types [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful lives	3 years
Maximum [Member] | Building, Machinery and Equipment, Gross [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful lives	50 years
Maximum [Member] | Geothermal Properties, Gross [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful lives	58 years
Maximum [Member] | Property, Plant and Equipment, Other Types [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful lives	50 years

Revenue From Contracts with C_3

Revenue From Contracts with Customers Disaggregation of Revenues (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2019		Jun. 30, 2018		Jun. 30, 2019		Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Commodity revenue		$ 2,128		$ 2,121		$ 4,666		$ 4,517
Revenues		2,599	[1]	2,259	[1]	5,198	[2]	4,268	[2]
West [Member]
Disaggregation of Revenue [Line Items]
Revenues		649	[1]	355	[1]	1,331	[2]	835	[2]
Texas [Member]
Disaggregation of Revenue [Line Items]
Revenues		899	[1]	993	[1]	1,642	[2]	1,133	[2]
East [Member]
Disaggregation of Revenue [Line Items]
Revenues		646	[1]	341	[1]	1,335	[2]	955	[2]
Retail [Member]
Disaggregation of Revenue [Line Items]
Revenues		1,082	[1]	935	[1]	2,080	[2]	1,873	[2]
Energy and Other Products [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		1,000		1,073		2,209		2,151
Energy and Other Products [Member] | West [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		145		176		437		375
Energy and Other Products [Member] | Texas [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		318		326		620		630
Energy and Other Products [Member] | East [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		124		120		327		252
Energy and Other Products [Member] | Retail [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		413		451		825		894
Energy and Other Products [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		0		0		0		0
Capacity Revenue [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		223		198		467		392
Capacity Revenue [Member] | West [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		36		35		71		54
Capacity Revenue [Member] | Texas [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		33		23		65		49
Capacity Revenue [Member] | East [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		154		140		331		289
Capacity Revenue [Member] | Retail [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		0		0		0		0
Capacity Revenue [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		0		0		0		0
Revenues Relating to Physical or Executory Contracts - Third Party [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		1,223		1,271		2,676		2,543
Revenues Relating to Physical or Executory Contracts - Third Party [Member] | West [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		181		211		508		429
Revenues Relating to Physical or Executory Contracts - Third Party [Member] | Texas [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		351		349		685		679
Revenues Relating to Physical or Executory Contracts - Third Party [Member] | East [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		278		260		658		541
Revenues Relating to Physical or Executory Contracts - Third Party [Member] | Retail [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		413		451		825		894
Revenues Relating to Physical or Executory Contracts - Third Party [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue		0		0		0		0
Affiliate Revenue [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	0		0		0		0
Affiliate Revenue [Member] | West [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	6		5		17		13
Affiliate Revenue [Member] | Texas [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	14		9		28		13
Affiliate Revenue [Member] | East [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	30		21		57		42
Affiliate Revenue [Member] | Retail [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	1		1		4		2
Affiliate Revenue [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Commodity revenue	[3]	(51)		(36)		(106)		(70)
Revenues Relating to Leases and Derivative Instruments [Member]
Disaggregation of Revenue [Line Items]
Revenues	[4]	$ 1,376		$ 988		$ 2,522		$ 1,725
[1]	Includes intersegment revenues of $100 million and $70 million in the West, $348 million and $276 million in Texas, $228 million and $18 million in the East and $1 million and $1 million in Retail for the three months ended June 30, 2019 and 2018, respectively.
[2]	Includes intersegment revenues of $262 million and $184 million in the West, $559 million and $209 million in Texas, $365 million and $133 million in the East and $4 million and $2 million in Retail for the six months ended June 30, 2019 and 2018, respectively.
[3]	Affiliate energy, other and capacity revenues reflect revenues on transactions between wholesale and retail affiliates excluding affiliate activity related to leases and derivative instruments. All such activity supports retail supply needs from the wholesale business and/or allows for collateral margin netting efficiencies at Calpine.
[4]	Revenues relating to contracts accounted for as leases and derivatives include energy and capacity revenues relating to PPAs that we are required to account for as operating leases and physical and financial commodity derivative contracts, primarily relating to power, natural gas and environmental products. Revenue related to derivative instruments includes revenue recorded in Commodity revenue and mark-to-market gain (loss) within our operating revenues on our Consolidated Condensed Statements of Operations.

Revenue From Contracts with C_4

Revenue From Contracts with Customers Performance Obligations Not Yet Satisfied (Details) - Capacity Revenue [Member] $ in Millions	Jun. 30, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 258
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 517
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 468
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 249
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 50
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 72
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period

Revenue From Contracts with C_5

Revenue From Contracts with Customers Performance Obligations and Contract Balances (Details) - Environmental Credits [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Deferred Revenue, Current	$ 22		$ 22		$ 14
Deferred Revenue, Revenue Recognized	$ 2	$ 3	$ 3	$ 9

Leases (Details)

Leases (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Operating Lease, Right-of-Use Asset	[1],[2]	$ 184
Operating Lease, Liability	[3],[4]	210
Capital Leased Assets, Gross			$ 715
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		6,860	6,832
Lesse Operating Lease, Lease Not yet Commenced		$ 1
Lessee, Finance Lease, Term of Contract		30 years
Finance Lease, Liability	[3],[5]	$ 78
Assets Held under Capital Leases [Member]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			$ 353
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Operating Lease, Right-of-Use Asset	[1],[2]	1
Operating Lease, Liability	[3],[4]	1
Finance Lease, Liability	[3],[4]	18
Finance Lease, Right-of-Use Asset	[1],[2]	$ 17
[1]	Excludes a right-of-use asset and property, plant and equipment, net of $1 million and $17 million, respectively, related to Garrison Energy Center which are included in current assets held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center.
[2]	The right-of-use assets associated with our operating leases as of June 30, 2019 are included in other assets on our Consolidated Condensed Balance Sheet.
[3]	Excludes an operating lease obligation of $1 million and a finance lease obligation of $18 million related to Garrison Energy Center which are included in current liabilities held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center.
[4]	The lease liabilities associated with our operating leases as of June 30, 2019 are included in other current liabilities and other long-term liabilities on our Consolidated Condensed Balance Sheet.
[5]	The lease liabilities associated with our finance leases as of June 30, 2019 are included in debt, current portion and debt, net of current portion on our Consolidated Condensed Balance Sheet.

Leases Future Minimum Lease Pay

Leases Future Minimum Lease Payments (Details) $ in Millions	Jun. 30, 2019USD ($)	[1]
Operating and Finance Leases [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 39	[2]
Finance Lease, Liability, Payments, Remainder of Fiscal Year	8	[3]
Lessee, Operating Lease, Liability, Payments, Due Year Two	20	[2]
Finance Lease, Liability, Payments, Due Year Two	16	[3]
Lessee, Operating Lease, Liability, Payments, Due Year Three	21	[2]
Finance Lease, Liability, Payments, Due Year Three	16	[3]
Lessee, Operating Lease, Liability, Payments, Due Year Four	19	[2]
Finance Lease, Liability, Payments, Due Year Four	16	[3]
Lessee, Operating Lease, Liability, Payments, Due Year Five	18	[2]
Finance Lease, Liability, Payments, Due Year Five	19	[3]
Lessee, Operating Lease, Liability, Payments, Due after Year Five	201	[2]
Finance Lease, Liability, Payments, Due after Year Five	33	[3]
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	108	[2]
Finance Lease, Liability, Undiscounted Excess Amount	30	[3]
Operating Lease, Liability	210	[2]
Finance Lease, Liability	78	[3]
Operating Lease, Liability, Current	39	[2]
Lessee, Operating Lease, Liability, Payments, Due	318	[2]
Finance Lease, Liability, Current	10	[3]
Finance Lease, Liability, Payment, Due	108	[3]
Operating Lease, Liability, Noncurrent	171	[2]
Finance Lease, Liability, Noncurrent	$ 68	[3]
[1]	Excludes an operating lease obligation of $1 million and a finance lease obligation of $18 million related to Garrison Energy Center which are included in current liabilities held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center.
[2]	The lease liabilities associated with our operating leases as of June 30, 2019 are included in other current liabilities and other long-term liabilities on our Consolidated Condensed Balance Sheet.
[3]	The lease liabilities associated with our finance leases as of June 30, 2019 are included in debt, current portion and debt, net of current portion on our Consolidated Condensed Balance Sheet.

Leases Supplemental balance she

Leases Supplemental balance sheet information (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment, Gross		$ 18,300	$ 18,187
Accumulated Depreciation		(6,860)	(6,832)
Property, plant and equipment, net		12,051	$ 12,442
Operating Lease, Right-of-Use Asset	[1],[2]	$ 184
Operating Lease, Weighted Average Remaining Lease Term	[1]	15 years 9 months 18 days
Finance Lease, Weighted Average Remaining Lease Term	[1]	7 years 4 months 24 days
Operating Lease, Weighted Average Discount Rate, Percent	[1]	5.10%
Finance Lease, Weighted Average Discount Rate, Percent	[1]	8.00%
Property Subject to Finance Lease [Member]
Property, Plant and Equipment, Gross	[1],[3]	$ 213
Accumulated Depreciation	[1],[3]	(104)
Property, plant and equipment, net	[1],[3]	$ 109
[1]	Excludes a right-of-use asset and property, plant and equipment, net of $1 million and $17 million, respectively, related to Garrison Energy Center which are included in current assets held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center.
[2]	The right-of-use assets associated with our operating leases as of June 30, 2019 are included in other assets on our Consolidated Condensed Balance Sheet.
[3]	The right-of-use assets associated with our finance leases as of June 30, 2019 are included in property, plant and equipment, net on our Consolidated Condensed Balance Sheet.

Leases Supplemental cash flow i

Leases Supplemental cash flow information (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019USD ($)
Supplemental Cash Flow Information [Abstract]
Operating Lease, Payments	$ 13
Finance Lease, Interest Payment on Liability	4
Finance Lease, Principal Payments	6
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	9
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 0

Leases Power plants subject to

Leases Power plants subject to tolling contracts (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment, Gross		$ 18,300	$ 18,187
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		6,860	6,832
Property, plant and equipment, net		12,051	$ 12,442
Property Subject to Operating Lease [Member]
Property, Plant and Equipment, Gross		3,076
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		903
Property, plant and equipment, net	[1]	$ 2,173
[1]	Our assets subject to contracts that are accounted for as operating leases primarily consist of our power plants subject to tolling contracts.

Leases Schedule of Future Minim

Leases Schedule of Future Minimum Rental Payments for Operating Leases (Details) $ in Millions	Dec. 31, 2018USD ($)
Schedule of Future Minimum Rental Payments for Operating Leases [Abstract]
Operating Leases, Future Minimum Payments Receivable, Current	$ 342
Operating Leases, Future Minimum Payments Receivable, in Two Years	261
Operating Leases, Future Minimum Payments Receivable, in Three Years	257
Operating Leases, Future Minimum Payments Receivable, in Four Years	224
Operating Leases, Future Minimum Payments Receivable, in Five Years	141
Operating Leases, Future Minimum Payments Receivable, Thereafter	239
Operating Leases, Future Minimum Payments Receivable	$ 1,464

Leases Maturity of Operating Le

Leases Maturity of Operating Lease Liabilities (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Maturity of Operating Lease Liabilities [Abstract]
Operating Leases, Future Minimum Payments Due, Next Twelve Months			$ 50
Capital Leases, Future Minimum Payments Due, Next Twelve Months	[1]		40
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	[2],[3]	$ 39
Finance Lease, Liability, Payments, Remainder of Fiscal Year	[2],[4]	8
Lessee, Operating Lease, Liability, Payments, Due Year Two			19
Capital Leases, Future Minimum Payments Due in Two Years	[1]		40
Finance Lease, Liability, Payments, Due Year Two	[2],[4]	16
Operating Leases, Future Minimum Payments, Due in Three Years			20
Capital Leases, Future Minimum Payments Due in Three Years	[1]		38
Lessee, Operating Lease, Liability, Payments, Due Year Three	[2],[3]	21
Finance Lease, Liability, Payments, Due Year Three	[2],[4]	16
Operating Leases, Future Minimum Payments, Due in Four Years			18
Capital Leases, Future Minimum Payments Due in Four Years	[1]		33
Lessee, Operating Lease, Liability, Payments, Due Year Four	[2],[3]	19
Finance Lease, Liability, Payments, Due Year Four	[2],[4]	16
Operating Leases, Future Minimum Payments, Due in Five Years			17
Capital Leases, Future Minimum Payments Due in Five Years	[1]		27
Lessee, Operating Lease, Liability, Payments, Due Year Five	[2],[3]	18
Finance Lease, Liability, Payments, Due Year Five	[2],[4]	19
Operating Leases, Future Minimum Payments, Due Thereafter			192
Capital Leases, Future Minimum Payments Due Thereafter	[1]		92
Lessee, Operating Lease, Liability, Payments, Due after Year Five	[2],[3]	201
Finance Lease, Liability, Payments, Due after Year Five	[2],[4]	33
Operating Leases, Future Minimum Payments Due			316
Lessee, Operating Lease, Liability, Payments, Due	[2],[3]	318
Finance Lease, Liability, Payment, Due	[2],[4]	108
Finance Lease, Liability, Undiscounted Excess Amount	[2],[4]	30
Finance Lease, Liability	[2],[4]	$ 78
Capital Leases, Future Minimum Payments Due	[1]		270
Capital Leases, Future Minimum Payments, Interest Included in Payments	[1]		89
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	[1]		$ 181
[1]	Includes a failed sale-leaseback transaction related to our Pasadena Power Plant.
[2]	Excludes an operating lease obligation of $1 million and a finance lease obligation of $18 million related to Garrison Energy Center which are included in current liabilities held for sale on our Consolidated Condensed Balance Sheet. See Note 4 for further information related to the sale of the Garrison Energy Center.
[3]	The lease liabilities associated with our operating leases as of June 30, 2019 are included in other current liabilities and other long-term liabilities on our Consolidated Condensed Balance Sheet.
[4]	The lease liabilities associated with our finance leases as of June 30, 2019 are included in debt, current portion and debt, net of current portion on our Consolidated Condensed Balance Sheet.

Leases Operating Leases, Future

Leases Operating Leases, Future Minimum Payments Receivable (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
		Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Operating Leases, Future Minimum Payments Receivable [Abstract]
Lessor, Operating Lease, Payments to be Received, Remainder of Fiscal Year		$ 204	$ 204
Operating Lease, Lease Income	[1]	70	139
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals				$ 342
Lessor, Operating Lease, Payments to be Received, Two Years		287	287
Lessor, Operating Lease, Payments to be Received, Three Years		261	261
Lessor, Operating Lease, Payments to be Received, Four Years		227	227
Lessor, Operating Lease, Payments to be Received, Five Years		144	144
Lessor, Operating Lease, Payments to be Received, Thereafter		284	284
Lessor, Operating Lease, Payments to be Received		$ 1,407	$ 1,407
[1]	Revenues associated with our operating leases are included in Commodity revenue and other revenue on our Consolidated Condensed Statement of Operations.

Leases Components of operating

Leases Components of operating and finance lease expense (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Components of our operating and finance lease expense [Abstract]
Operating Lease, Cost	$ 12	$ 23
Finance Lease, Right-of-Use Asset, Amortization	1	4
Finance Lease, Interest Expense	2	4
Finance lease, expense, Total	3	8
Variable Lease, Cost	4	5
Lease, Cost	$ 19	$ 36

Divestitures (Details)

Divestitures (Details) $ in Millions	3 Months Ended				6 Months Ended
	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Jun. 30, 2019USD ($)		Jun. 30, 2018USD ($)		Jul. 10, 2019MW
Business Acquisition [Line Items]
Dividends paid(2)				$ (20)	$ 0	[1]	$ (18)	[1]
Impairment losses		$ 40	$ 0		$ 55		$ 0
Subsequent Event [Member]
Business Acquisition [Line Items]
Dividends paid(2)	$ 400
Subsequent Event [Member] | Garrison Energy Center and RockGen Energy LLC [Member]
Business Acquisition [Line Items]
Ownership percentage of acquiree									100.00%
Proceeds from Sale of Productive Assets	$ 360
Subsequent Event [Member] | Garrison Energy Center LLC [Member]
Business Acquisition [Line Items]
Power generation capacity | MW									309
Subsequent Event [Member] | RockGen Energy LLC [Member]
Business Acquisition [Line Items]
Power generation capacity | MW									503
[1]	Subsequent to the consummation of the Merger on March 8, 2018, we paid certain Merger-related costs incurred by CPN Management, our direct parent.

Variable Interest Entities an_3

Variable Interest Entities and Unconsolidated Investments in Power Plants (Unconsolidated VIEs) (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 71	$ 76
Equity method investment, ownership percentage		50.00%
Greenfield [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	$ 56	55
Equity method investment, ownership percentage		50.00%
Whitby [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 10	15
Equity method investment, ownership percentage		50.00%
Calpine Receivables [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 5	$ 6
Equity method investment, ownership percentage		100.00%
[1]	Includes our share of accumulated other comprehensive income/loss related to interest rate hedging instruments associated with our unconsolidated subsidiary Greenfield LP’s debt.

Variable Interest Entities an_4

Variable Interest Entities and Unconsolidated Investments in Power Plants (Income from Unconsolidated Investments 10-Q) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
(Income) from unconsolidated subsidiaries	$ (5)	$ (5)	$ (11)	$ (11)
Greenfield [Member]
(Income) from unconsolidated subsidiaries	(4)	(2)	(6)	(4)
Whitby [Member]
(Income) from unconsolidated subsidiaries	(2)	(4)	(6)	(8)
Calpine Receivables [Member]
(Income) from unconsolidated subsidiaries	$ 1	$ 1	$ 1	$ 1

Variable Interest Entities an_5

Variable Interest Entities and Unconsolidated Investments in Power Plants (VIE Texuals) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019USD ($)yrMW	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)yrMW	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)MW
Variable Interest Entity [Line Items]
Variable interest entity, financial or other support, amount	$ 0	$ 0	$ 0	$ 0
Equity method investment, ownership percentage	50.00%		50.00%
Equity method investment, summarized financial information, debt	$ 304		$ 304		$ 301
Prorata share of equity method investment, summarized financial information, debt	$ 152		152		$ 151
Return on investments from unconsolidated subsidiaries			$ 11	5
Greenfield [Member]
Variable Interest Entity [Line Items]
Power generation capacity | MW	1,038		1,038
Equity method investment, ownership percentage	50.00%		50.00%
Return on investments from unconsolidated subsidiaries	$ 0	0	$ 0	0
Whitby [Member]
Variable Interest Entity [Line Items]
Power generation capacity | MW	50		50
Equity method investment, ownership percentage	50.00%		50.00%
Return on investments from unconsolidated subsidiaries	$ 0	$ 2	$ 11	$ 5
Calpine Receivables [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 67		$ 67
Equity method investment, ownership percentage	100.00%		100.00%
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Power generation capacity | MW	7,880		7,880		7,880
Put Option [Member]
Variable Interest Entity [Line Items]
Proceeds from sale of property, plant and equipment			$ 280
Call Option [Member]
Variable Interest Entity [Line Items]
Proceeds from sale of property, plant and equipment			$ 377
Inland Empire Energy Center [Member]
Variable Interest Entity [Line Items]
Power generation capacity | MW	775		775
Put Option Exercise Period | yr	2,025		2,025
Inland Empire Energy Center [Member] | Minimum [Member]
Variable Interest Entity [Line Items]
Call Option Exercise Period | yr	2,017		2,017
Inland Empire Energy Center [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Call Option Exercise Period | yr	2,024		2,024
OMEC [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	$ 220		$ 220

Debt (Debt) (Details)

Debt (Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt and Lease Obligation	$ 10,724	$ 10,785
Debt, Current	263	637
Long-term Debt, Excluding Current Maturities	10,461	10,148
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	2,990	3,036
Loans Payable [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	2,979	2,976
Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	2,402	2,400
Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	1,229	1,264
Secured Debt [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	971	974
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	78	105
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	$ 75	$ 30

Debt Senior Unsecured Notes (De

Debt Senior Unsecured Notes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term Debt	$ 10,677		$ 10,677		$ 10,156
Gain (Loss) on Extinguishment of Debt	(3)	$ 0	1	$ 0
Senior Unsecured Notes 2023 [Member]
Debt Instrument [Line Items]
Long-term Debt	1,228		1,228		1,227
Senior Unsecured Notes 2024 [Member]
Debt Instrument [Line Items]
Long-term Debt	589		589		599
Senior Unsecured Notes 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt	1,173		1,173		1,210
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount, Cumulative	438		438
Debt Instrument, Repurchased Face Amount	48		48
Long-term Debt	2,990		2,990		$ 3,036
Debt Instrument, Repurchase Amount	44		44
Gain (Loss) on Extinguishment of Debt			4
Debt Instrument, Repurchase Amount, Cumulative	$ 399		$ 399

Debt (First Lien Term Loans) (D

Debt (First Lien Term Loans) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term Debt	$ 10,677	$ 10,156
New 2019 First Lien Term Loan [Member]
Debt Instrument [Line Items]
Long-term Debt	0	389
2023 First Lien Term Loan [Member]
Debt Instrument [Line Items]
Long-term Debt	535	1,059
2024 First Lien Term Loan [Member]
Debt Instrument [Line Items]
Long-term Debt	1,522	1,528
2026 First Lien Term Loan [Member]
Debt Instrument [Line Items]
Long-term Debt	922	0
First Lien Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 2,979	$ 2,976

Debt (First Lien Notes) (Detail

Debt (First Lien Notes) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term Debt	$ 10,677	$ 10,156
2022 First Lien Notes [Member]
Debt Instrument [Line Items]
Long-term Debt	744	743
2024 First Lien Notes [Member]
Debt Instrument [Line Items]
Long-term Debt	487	486
2026 First Lien Notes [Member]
Debt Instrument [Line Items]
Long-term Debt	1,171	1,171
Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 2,402	$ 2,400

Debt (Letter of Credit) (Detail

Debt (Letter of Credit) (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount		$ 1,135	$ 1,365
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	[1]	585	693
CDH [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	[2]	30	251
Various Project Financing Facilities [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount		227	228
Other Corporate Facilities [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	[3]	$ 293	$ 193
[1]	The Corporate Revolving Facility represents our primary revolving facility. On April 5, 2019, we amended our Corporate Revolving Facility to increase the capacity by approximately $330 million from $1.69 billion to approximately $2.02 billion.
[2]	Pursuant to the terms and conditions of the CDHI credit agreement, the capacity under the CDHI letter of credit facility was reduced to $125 million on June 28, 2019. The decrease in capacity did not have a material effect on our liquidity as alternative sources of liquidity are available.
[3]	We have three unsecured letter of credit facilities with two third-party financial institutions totaling approximately $300 million at June 30, 2019.

Debt (Fair Value of Debt) (Deta

Debt (Fair Value of Debt) (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		$ 10,677	$ 10,156
Unsecured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		2,990	3,036
Loans Payable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		2,979	2,976
Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		2,402	2,400
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		10,570	10,604
Reported Value Measurement [Member] | Unsecured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		2,990	3,036
Reported Value Measurement [Member] | Loans Payable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		2,979	2,976
Reported Value Measurement [Member] | Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		2,402	2,400
Reported Value Measurement [Member] | Notes Payable, Other Payable excluding Capital Leases [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	[1]	1,153	1,188
Reported Value Measurement [Member] | Secured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		971	974
Reported Value Measurement [Member] | Revolving Credit Facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		75	30
Fair Value, Inputs, Level 2 [Member] | Unsecured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		3,011	2,803
Fair Value, Inputs, Level 2 [Member] | Loans Payable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		3,013	2,877
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		2,462	2,299
Fair Value, Inputs, Level 2 [Member] | Secured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		980	938
Fair Value, Inputs, Level 2 [Member] | Revolving Credit Facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt		75	30
Fair Value, Inputs, Level 3 [Member] | Notes Payable, Other Payable excluding Capital Leases [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	[1]	$ 1,136	$ 1,209
[1]	Excludes an agreement that is accounted for as a failed sale-leaseback transaction under U.S. GAAP.

Debt (Debt Textuals) (Details)

Debt (Debt Textuals) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Apr. 05, 2019
Line of Credit Facility [Line Items]
Gain (Loss) on Extinguishment of Debt	$ (3)	$ 0	$ 1	$ 0
Debt Instruments [Abstract]
Debt Instrument, Interest Rate, Effective Percentage	5.90%	5.70%	5.90%	5.70%
CDHI [Member]
Line of Credit Facility [Line Items]
Future Line of Credit Facility Maximum Borrowing Capacity	$ 125		$ 125
Other Corporate Facilities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 300		300
2026 First Lien Term Loan [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount					$ 950
Percentage of principal amount of Term Loan to be paid quarterly	0.25%
Debt Instrument Unamortized Discount Percent					1.00%
Debt Issuance Costs, Net					$ 7
Gain (Loss) on Extinguishment of Debt	$ (3)
Russell City and Los Esteros Project Debt [Member]
Line of Credit Facility [Line Items]
Long-term Debt, Excluding Current Maturities	362		362
Amendment No. 6 [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Increase (Decrease), Net	330
Line of Credit Facility, Maximum Borrowing Capacity					$ 2,020
Amendment No. 8 [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,690		$ 1,690
Federal Funds Effective Rate [Member] | 2026 First Lien Term Loan [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
Eurodollar Rate For A One-Month Interest Period [Member] | 2026 First Lien Term Loan [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Prime Rate or The Eurodollar Rate For A One-Month Interest Period [Member] | 2026 First Lien Term Loan [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
London Interbank Offered Rate (LIBOR) [Member] | 2026 First Lien Term Loan [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.75%
Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member] | 2026 First Lien Term Loan [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					0.00%

Assets and Liabilities with R_3

Assets and Liabilities with Recurring Fair Value Measurements Fair Value Hierarchy (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	$ 165	$ 168
Derivative Asset	[2]	415	302
Effect of Netting and Allocation of Collateral	[3],[4]	(1,352)	(1,221)
Total assets		580	470
Derivative Liability	[2]	284	443
Effect of Netting and Allocation of Collateral, Liability	[3],[4]	(1,498)	(1,268)
Total Liabilities		284	443
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	165	168
Effect of Netting and Allocation of Collateral	[3],[4]	(1,089)	(933)
Total assets		165	168
Effect of Netting and Allocation of Collateral, Liability	[3],[4]	(1,179)	(932)
Total Liabilities		0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	0	0
Effect of Netting and Allocation of Collateral	[3],[4]	(243)	(262)
Total assets		113	116
Effect of Netting and Allocation of Collateral, Liability	[3],[4]	(298)	(310)
Total Liabilities		209	249
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	0	0
Effect of Netting and Allocation of Collateral	[3],[4]	(20)	(26)
Total assets		302	186
Effect of Netting and Allocation of Collateral, Liability	[3],[4]	(21)	(26)
Total Liabilities		75	194
Future [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		1,089	933
Derivative Liability		1,179	932
Future [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		1,089	933
Derivative Liability		1,179	932
Future [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0	0
Derivative Liability		0	0
Future [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0	0
Derivative Liability		0	0
Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	[5]	672	550
Derivative Liability	[5]	570	769
Forward Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	[5]	0	0
Derivative Liability	[5]	0	0
Forward Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	[5]	350	338
Derivative Liability	[5]	474	549
Forward Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	[5]	322	212
Derivative Liability	[5]	96	220
Interest Rate Hedging Instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		6	40
Derivative Liability		33	10
Interest Rate Hedging Instruments | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0	0
Derivative Liability		0	0
Interest Rate Hedging Instruments | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		6	40
Derivative Liability		33	10
Interest Rate Hedging Instruments | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0	0
Derivative Liability		$ 0	$ 0
[1]	At June 30, 2019 and December 31, 2018, we had cash equivalents of $16 million and $23 million included in cash and cash equivalents and $149 million and $145 million included in restricted cash, respectively.
[2]	At June 30, 2019 and December 31, 2018, we had $142 million and $244 million, respectively, of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets primarily related to initial margin requirements.
[3]	Cash collateral posted with (received from) counterparties allocated to level 1, level 2 and level 3 derivative instruments totaled $90 million, $55 million and $1 million, respectively, at June 30, 2019. Cash collateral posted with (received from) counterparties allocated to level 1, level 2 and level 3 derivative instruments totaled $(1) million, $48 million and nil, respectively, at December 31, 2018.
[4]	We offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation; therefore, amounts recognized for the right to reclaim, or the obligation to return, cash collateral are presented net with the corresponding derivative instrument fair values. See Note 8 for further discussion of our derivative instruments subject to master netting arrangements.
[5]	Includes OTC swaps and options.

Assets and Liabilities with R_4

Assets and Liabilities with Recurring Fair Value Measurements Quantitative Info on Level 3 (Details) - USD ($)		Jun. 30, 2019	Dec. 31, 2018
Fair Value Measurements Inputs and Valuation Techniques
Derivative, Fair Value, Net	[1]	$ 131,000,000	$ (141,000,000)
Power Contracts [Member]
Fair Value Measurements Inputs and Valuation Techniques
Derivative, Fair Value, Net	[2]	190,000,000	36,000,000
Power Contracts [Member] | Minimum [Member]
Fair Value Measurements Inputs and Valuation Techniques
Fair Value Inputs Quantitative Information		7.09	2.12
Power Contracts [Member] | Maximum [Member]
Fair Value Measurements Inputs and Valuation Techniques
Fair Value Inputs Quantitative Information		123.34	227.98
Natural Gas [Member]
Fair Value Measurements Inputs and Valuation Techniques
Derivative, Fair Value, Net		6,000,000	(73,000,000)
Natural Gas [Member] | Minimum [Member]
Fair Value Measurements Inputs and Valuation Techniques
Fair Value Inputs Quantitative Information		0.61	0.75
Natural Gas [Member] | Maximum [Member]
Fair Value Measurements Inputs and Valuation Techniques
Fair Value Inputs Quantitative Information		9.75	8.87
Power Congestion Products [Member]
Fair Value Measurements Inputs and Valuation Techniques
Derivative, Fair Value, Net		18,000,000	26,000,000
Power Congestion Products [Member] | Minimum [Member]
Fair Value Measurements Inputs and Valuation Techniques
Fair Value Inputs Quantitative Information		(8.63)	(11.71)
Power Congestion Products [Member] | Maximum [Member]
Fair Value Measurements Inputs and Valuation Techniques
Fair Value Inputs Quantitative Information		$ 11.48	$ 11.88
[1]	At June 30, 2019 and December 31, 2018, we had $142 million and $244 million, respectively, of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets primarily related to initial margin requirements.
[2]	Power contracts include power and heat rate instruments classified as level 3 in the fair value hierarchy.

Assets and Liabilities with R_5

Assets and Liabilities with Recurring Fair Value Measurements (Textuals) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Fair Value Measurement [Domain]
Fair Value Disclosures [Abstract]
Cash and Cash Equivalents, at Carrying Value		$ 16		$ 16		$ 23
Restricted Cash and Cash Equivalents		149		149		145
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs		105	$ 129	(8)	$ 197
Included in operating revenues	[1]	152	31	197	(28)
Fair Value, Assets Measured with Unobservable Inputs on Recurring Basis, Gain (Loss) Included In Fuel And Purchased Energy Expense	[2]	1	18	2	15
Amount of Change in Collateral of Financial Instruments Classified as Derivative Asset (Liability)		(1)	1	1	(1)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases		1	5	3	9
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Issues		(1)	0	(1)	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(35)	(42)	28	(53)
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount		0	0	0	0
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount		0	0	0	0
Transfers into level 3	[3],[4]	6	(1)	7	(1)
Transfers out of Level 3	[4],[5]	(1)	(10)	(2)	(7)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs		227	131	227	131
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		153	$ 49	199	$ (13)
Cash and Cash Equivalents, at Carrying Value		297		297		205
Restricted Cash and Cash Equivalents		262		262		201
Fair Value, Inputs, Level 1 [Member]
Fair Value Disclosures [Abstract]
Derivative, Collateral, Right to Reclaim Cash, Net		90		90		(1)
Fair Value, Inputs, Level 2 [Member]
Fair Value Disclosures [Abstract]
Derivative, Collateral, Right to Reclaim Cash, Net		55		55		48
Fair Value, Inputs, Level 3 [Member]
Fair Value Disclosures [Abstract]
Derivative, Collateral, Right to Reclaim Cash, Net		$ 1		$ 1		$ 0
[1]	For power contracts and other power-related products, included on our Consolidated Condensed Statements of Operations.
[2]	For natural gas and power contracts, swaps and options, included on our Consolidated Condensed Statements of Operations.
[3]	We had $6 million in gains and $(1) million in losses transferred out of level 2 into level 3 for the three months ended June 30, 2019 and 2018, respectively, and $7 million in gains and $(1) million in losses transferred out of level 2 into level 3 for the six months ended June 30, 2019 and 2018, respectively, due to changes in market liquidity in various power markets.
[4]	We transfer amounts among levels of the fair value hierarchy as of the end of each period. There were no transfers into or out of level 1 for each of the three and six months ended June 30, 2019 and 2018.
[5]	We had $1 million and $10 million in gains transferred out of level 3 into level 2 for the three months ended June 30, 2019 and 2018, respectively, and $2 million and $7 million in gains transferred out of level 3 into level 2 for the six months ended June 30, 2019 and 2018, respectively, due to changes in market liquidity in various power markets.

Derivative Instruments (Details

Derivative Instruments (Details) $ in Billions	6 Months Ended	12 Months Ended
	Jun. 30, 2019USD ($)MMBTUMWht	Dec. 31, 2018USD ($)MMBTUMWht
Power [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MWh	181	161
Natural Gas [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	1,048	1,045
Environmental Credits [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | t	13	13
Interest Rate Hedging Instruments
Derivative [Line Items]
Derivative, Notional Amount | $	$ 4.3	$ 4.5

Derivative Instruments (Detai_2

Derivative Instruments (Details 2) (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative Asset	[1]	$ 415	$ 302
Derivative Liability	[1]	284	443
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		2	40
Derivative Liability		27	10
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		413	262
Derivative Liability		257	433
Interest Rate Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative Asset		6	40
Derivative Liability		33	10
Interest Rate Hedging Instruments | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		2	40
Derivative Liability		27	10
Interest Rate Hedging Instruments | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		0	0
Derivative Liability		2	0
Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		413	262
Derivative Liability		$ 255	$ 433
[1]	At June 30, 2019 and December 31, 2018, we had $142 million and $244 million, respectively, of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets primarily related to initial margin requirements.

Derivative Instruments (Detail

Derivative Instruments (Detail 3) (Details) - USD ($) $ in Millions		Jun. 30, 2019		Dec. 31, 2018
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative assets, current	[1]	$ 202	[2]	$ 142	[3]
Derivative Asset, Noncurrent	[1]	213	[2]	160	[3]
Long-term derivative liabilities	[1]	(119)	[2]	(140)	[3]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(15)		188
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		146		47
Derivative Liability, Current	[1]	(165)	[2]	(303)	[3]
Derivative Liability	[1]	(284)		(443)
Derivative, Collateral, Right to Reclaim Cash		142		244
Derivative, Fair Value, Net	[1]	131		(141)
Derivative Asset	[1]	415		302
Derivative Financial Instruments, Assets [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		1,767		1,523
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(1,352)		(1,221)
Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative assets, current	[1]	0		0
Derivative Asset, Noncurrent	[1]	0		0
Long-term derivative liabilities	[1]	0		0
Derivative Liability, Current	[1]	0		0
Derivative Liability		(1,179)		(932)
Derivative Asset		1,089		933
Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative assets, current	[1]	200		112
Derivative Asset, Noncurrent	[1]	213		150
Long-term derivative liabilities	[1]	(96)		(134)
Derivative Liability, Current	[1]	(159)		(299)
Derivative Liability	[4]	(570)		(769)
Derivative Asset	[4]	672		550
Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative assets, current	[1]	2		30
Derivative Asset, Noncurrent	[1]	0		10
Long-term derivative liabilities	[1]	(23)		(6)
Derivative Liability, Current	[1]	(6)		(4)
Derivative Liability		(33)		(10)
Derivative Asset		6		40
Fair Value, Inputs, Level 3 [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Margin/Cash (Received) Posted Subject to Master Netting Arrangement		1		0
Fair Value, Inputs, Level 3 [Member] | Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability		0		0
Derivative Asset		0		0
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability	[4]	(96)		(220)
Derivative Asset	[4]	322		212
Fair Value, Inputs, Level 3 [Member] | Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability		0		0
Derivative Asset		0		0
Derivative Assets, Current [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		1,254	[2]	1,191	[3]
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(1,052)	[2]	(1,049)	[3]
Derivative Assets, Current [Member] | Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		861		820
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(861)		(820)
Derivative Assets, Current [Member] | Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		388		341
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(188)		(229)
Derivative Assets, Current [Member] | Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		5		30
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(3)		0
Derivative Assets, Non-current [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		513	[2]	332	[3]
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(300)	[2]	(172)	[3]
Derivative Assets, Non-current [Member] | Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		228		113
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(228)		(113)
Derivative Assets, Non-current [Member] | Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		284		209
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(71)		(59)
Derivative Assets, Non-current [Member] | Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		1		10
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(1)		0
Derivative Liabilities, Current [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(1,263)	[2]	(1,344)	[3]
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		1,098	[2]	1,041	[3]
Derivative Liabilities, Current [Member] | Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(861)		(764)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		861		764
Derivative Liabilities, Current [Member] | Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(393)		(576)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		234		277
Derivative Liabilities, Current [Member] | Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(9)		(4)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		3		0
Derivative Liabilities, Non-current [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(519)	[2]	(367)	[3]
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		400	[2]	227	[3]
Derivative Liabilities, Non-current [Member] | Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(318)		(168)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		318		168
Derivative Liabilities, Non-current [Member] | Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(177)		(193)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		81		59
Derivative Liabilities, Non-current [Member] | Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(24)		(6)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		1		0
Derivative Financial Instruments, Liabilities [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(1,782)		(1,711)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		$ 1,498		$ 1,268
[1]	At June 30, 2019 and December 31, 2018, we had $142 million and $244 million, respectively, of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets primarily related to initial margin requirements.
[2]	At June 30, 2019, current and long-term derivative assets are shown net of collateral of $(27) million and $(3) million, respectively, and current and long-term derivative liabilities are shown net of collateral of $72 million and $104 million, respectively.
[3]	At December 31, 2018, current and long-term derivative assets are shown net of collateral of $(58) million and $(8) million, respectively, and current and long-term derivative liabilities are shown net of collateral of $49 million and $64 million, respectively.
[4]	Includes OTC swaps and options.

Derivative Instruments (Detai_3

Derivative Instruments (Details 4) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Summary of Derivative Instruments by Risk Exposure [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	[1]	$ 244	$ 258	$ 400	$ (114)
Gain (Loss) on Sale of Derivatives	[2],[3]	58	69	169	66
Mark-to-market gain (loss)	[4]	186	189	231	(180)
Sales [Member]
Summary of Derivative Instruments by Risk Exposure [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	[1],[5],[6]	541	183	578	(176)
Cost of Sales [Member]
Summary of Derivative Instruments by Risk Exposure [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	[1],[5],[6]	(296)	74	(176)	59
Interest Expense [Member]
Summary of Derivative Instruments by Risk Exposure [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	[1]	(1)	1	(2)	3
Interest Rate Hedging Instruments
Summary of Derivative Instruments by Risk Exposure [Abstract]
Mark-to-market gain (loss)	[4]	(1)	1	(2)	3
Energy Related Derivative [Member]
Summary of Derivative Instruments by Risk Exposure [Abstract]
Gain (Loss) on Sale of Derivatives	[2],[3]	58	69	169	66
Mark-to-market gain (loss)	[4]	$ 187	$ 188	$ 233	$ (183)
[1]	In addition to changes in market value on derivatives not designated as hedges, changes in mark-to-market gain (loss) also includes adjustments to reflect changes in credit default risk exposure.
[2]	Does not include the realized value associated with derivative instruments that settle through physical delivery.
[3]	Includes amortization of acquisition date fair value of financial derivative activity related to the acquisition of Champion Energy and Calpine Solutions.
[4]	In addition to changes in market value on derivatives not designated as hedges, changes in mark-to-market gain (loss) also includes adjustments to reflect changes in credit default risk exposure.
[5]	Does not include the realized value associated with derivative instruments that settle through physical delivery.
[6]	Includes amortization of acquisition date fair value of financial derivative activity related to the acquisition of Champion Energy and Calpine Solutions.

Derivative Instruments (Detai_4

Derivative Instruments (Details 5) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax		$ (32)	$ 15	$ (57)	$ 70
Reclassification adjustment for loss on cash flow hedges realized in net income (loss)	[1],[2]	3	0	5	(7)
Depreciation expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax	[3],[4]			0	1
Reclassification adjustment for loss on cash flow hedges realized in net income (loss)	[1],[2],[3],[4]			0	(1)
Interest Rate Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax	[3],[4]	(32)	15	(57)	69
Reclassification adjustment for loss on cash flow hedges realized in net income (loss)	[1],[2],[3],[4]	$ 3	$ 0	$ 5	$ (6)
[1]	Cumulative cash flow hedge losses attributable to Calpine, net of tax, remaining in AOCI were $89 million and $34 million at June 30, 2019 and December 31, 2018, respectively. Cumulative cash flow hedge losses attributable to the noncontrolling interest, net of tax, remaining in AOCI were $4 million and $3 million at June 30, 2019 and December 31, 2018, respectively.
[2]	Includes losses (gains) of nil that were reclassified from AOCI to interest expense for the three months ended June 30, 2019 and 2018, and losses of $1 million and nil that were reclassified from AOCI to interest expense for the six months ended June 30, 2019 and 2018, respectively, where the hedged transactions became probable of not occurring.
[3]	We recorded $1 million in gains on hedge ineffectiveness related to our interest rate hedging instruments designated as cash flow hedges during each of the three and six months ended June 30, 2018. Upon the adoption of Accounting Standards Update 2017-12 on January 1, 2019, hedge ineffectiveness is no longer separately measured and recorded in earnings.
[4]	We recorded an income tax benefit of $1 million and $7 million for the three months ended June 30, 2019 and 2018, respectively, and income tax benefit of $1 million and income tax expense of $4 million for the six months ended June 30, 2019 and 2018, respectively, in AOCI related to our cash flow hedging activities.

Derivative Instruments (Textual

Derivative Instruments (Textuals) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net		$ 1,000,000		$ 1,000,000
Current Derivatives Assets, net of Collateral	$ (27,000,000)		$ (27,000,000)		$ (58,000,000)
Long-Term Derivative Assets, net of Collateral	(3,000,000)		(3,000,000)		(8,000,000)
Current Derivative Liabilities, net of Collateral	72,000,000		72,000,000		49,000,000
Long-term Derivative Liabilities, net of Collateral	104,000,000		104,000,000		64,000,000
Derivative, Collateral, Right to Reclaim Cash	142,000,000		142,000,000		244,000,000
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	1,000,000	(7,000,000)	$ (1,000,000)	(4,000,000)
Summary of Derivative Instruments [Abstract]
Maximum length of time hedging using interest rate derivative instruments			6 years
Derivative, Net Liability Position, Aggregate Fair Value	230,000,000		$ 230,000,000
Collateral Already Posted, Aggregate Fair Value	171,000,000		171,000,000
Additional Collateral, Aggregate Fair Value	5,000,000		5,000,000
Gain (Loss) on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	0	$ 0	1,000,000	$ 0
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months			20,000,000
Parent [Member]
Derivatives, Fair Value [Line Items]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	89,000,000		89,000,000		34,000,000
Noncontrolling Interest [Member]
Derivatives, Fair Value [Line Items]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	$ 4,000,000		$ 4,000,000		$ 3,000,000

Use of Collateral (Details)

Use of Collateral (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Financial Instruments Owned and Pledged as Collateral [Line Items]
Margin deposits	[1]	$ 373	$ 343
Natural gas and power prepayments		34	31
Total margin deposits and natural gas and power prepayments with our counterparties	[2]	407	374
Letters of credit issued		900	1,166
First priority liens under power and natural gas agreements		42	92
First priority liens under interest rate hedging instruments		29	10
Total letters of credit and first priority liens with our counterparties		971	1,268
Margin deposits held by us posted by our counterparties	[1],[3]	85	52
Letters of credit posted with us by our counterparties		31	27
Total margin deposits and letters of credit posted with us by our counterparties		116	79
Current and Non-current Derivative Assets and Liabilities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total margin deposits and natural gas and power prepayments with our counterparties	[2]	162	79
Margin deposits held by us posted by our counterparties		16	32
Other Current Liabilities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Margin deposits held by us posted by our counterparties		28	20
Prepaid Expenses and Other Current Assets [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total margin deposits and natural gas and power prepayments with our counterparties	[2]	237	286
Other Assets [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total margin deposits and natural gas and power prepayments with our counterparties	[2]	8	9
Other Noncurrent Liabilities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Margin deposits held by us posted by our counterparties		$ 41	$ 0
[1]	We offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation; therefore, amounts recognized for the right to reclaim, or the obligation to return, cash collateral are presented net with the corresponding derivative instrument fair values. See Note 8 for further discussion of our derivative instruments subject to master netting arrangements.
[2]	At June 30, 2019 and December 31, 2018, $162 million and $79 million, respectively, were included in current and long-term derivative assets and liabilities, $237 million and $286 million, respectively, were included in margin deposits and other prepaid expense and $8 million and $9 million, respectively, were included in other assets on our Consolidated Condensed Balance Sheets.
[3]	At June 30, 2019 and December 31, 2018, $16 million and $32 million, respectively, were included in current and long-term derivative assets and liabilities, $28 million and $20 million, respectively, were included in other current liabilities and $41 million and nil, respectively, were included in other long-term liabilities on our Consolidated Condensed Balance Sheets.

Income Taxes (Income Tax Expens

Income Taxes (Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Contingency [Line Items]
Income tax expense (benefit)	$ 9	$ (158)	$ 19	$ (50)
Effective Income Tax Rate, Continuing Operations	3.00%	(81.00%)	4.00%	17.00%
Income Tax Uncertainties [Abstract]
Unrecognized Tax Benefits	$ 29		$ 29
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	17		17
Unrecognized Tax Benefit Related to Deferred Tax Asset	12		12
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	3		3
Minimum [Member]
Income Tax Contingency [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	0		0
Maximum [Member]
Income Tax Contingency [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 8		$ 8

Commitments and Contingencies C

Commitments and Contingencies Commitments and Contingencies (Details) $ in Millions	Jun. 30, 2019USD ($)
Other Commitments [Line Items]
Guarantor Obligations, Current Carrying Value	$ 0

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Related Party Transactions [Abstract]
Continuing Involvement with Derecognized Transferred Financial Assets, Amount Outstanding	$ 244		$ 244		$ 238
Notes Receivable, Related Parties, Current	57		57		$ 34
Trade Receivables Sold			1,100	$ 1,100
Cash Flows Between Transferor and Transferee, Proceeds from New Transfers			1,100	1,100
Revenue from Related Parties	17	$ 19	37	38
Related Party Transaction, Purchases from Related Party	$ 4	$ 4	$ 7	$ 6

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019		Jun. 30, 2018		Jun. 30, 2019		Jun. 30, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues(1)	$ 2,599	[1]	$ 2,259	[1]	$ 5,198	[2]	$ 4,268	[2]
Commodity Margin	752		694		1,531		1,306
Add: Mark-to-market commodity activity, net and other(2)	200	[3]	196	[3]	252	[4]	(177)	[4]
Operating and maintenance expense	245		242		484		517
Depreciation and amortization expense	175		186		349		387
General and other administrative expense	34		31		66		91
Other operating expenses	19		19		38		56
Impairment losses	40		0		55		0
(Income) loss from unconsolidated investments in power plants	(5)		(5)		(11)		(11)
Income from operations	444		417		802		89
Interest expense	157		157		306		308
Debt Extinguishment Costs and Other (Income) Expense, Net	8		62		27		69
Income (loss) before income taxes	279		198		469		(288)
Lease levelization	(19)		(19)		(35)		(35)
West [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues(1)	649	[1]	355	[1]	1,331	[2]	835	[2]
Commodity Margin	251		241		515		426
Add: Mark-to-market commodity activity, net and other(2)	58	[3]	(23)	[3]	114	[4]	(10)	[4]
Operating and maintenance expense	84		80		165		170
Depreciation and amortization expense	60		67		133		134
General and other administrative expense	5		5		12		21
Other operating expenses	7		8		16		22
Impairment losses	0				0
(Income) loss from unconsolidated investments in power plants	0		0		0		0
Income from operations	153		58		303		69
Texas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues(1)	899	[1]	993	[1]	1,642	[2]	1,133	[2]
Commodity Margin	173		151		335		317
Add: Mark-to-market commodity activity, net and other(2)	240	[3]	301	[3]	284	[4]	(246)	[4]
Operating and maintenance expense	66		65		131		145
Depreciation and amortization expense	54		57		99		133
General and other administrative expense	15		13		27		38
Other operating expenses	1		3		3		19
Impairment losses	0				0
(Income) loss from unconsolidated investments in power plants	0		0		0		0
Income from operations	277		314		359		(264)
East [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues(1)	646	[1]	341	[1]	1,335	[2]	955	[2]
Commodity Margin	235		225		500		409
Add: Mark-to-market commodity activity, net and other(2)	94	[3]	(7)	[3]	107	[4]	33	[4]
Operating and maintenance expense	72		65		139		136
Depreciation and amortization expense	48		49		91		94
General and other administrative expense	10		8		19		23
Other operating expenses	11		8		19		15
Impairment losses	40				55
(Income) loss from unconsolidated investments in power plants	(6)		(6)		(12)		(12)
Income from operations	154		94		296		186
Retail [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues(1)	1,082	[1]	935	[1]	2,080	[2]	1,873	[2]
Commodity Margin	93		77		181		154
Add: Mark-to-market commodity activity, net and other(2)	(182)	[3]	(67)	[3]	(235)	[4]	61	[4]
Operating and maintenance expense	33		41		67		81
Depreciation and amortization expense	13		13		26		26
General and other administrative expense	4		5		8		9
Other operating expenses	0		0		0		0
Impairment losses	0				0
(Income) loss from unconsolidated investments in power plants	1		1		1		1
Income from operations	(140)		(50)		(156)		98
Consolidation, Eliminations [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues(1)	(677)	[1]	(365)	[1]	(1,190)	[2]	(528)	[2]
Commodity Margin	0		0		0		0
Add: Mark-to-market commodity activity, net and other(2)	(10)	[3]	(8)	[3]	(18)	[4]	(15)	[4]
Operating and maintenance expense	(10)		(9)		(18)		(15)
Depreciation and amortization expense	0		0		0		0
General and other administrative expense	0		0		0		0
Other operating expenses	0		0		0		0
Impairment losses	0				0
(Income) loss from unconsolidated investments in power plants	0		0		0		0
Income from operations	0		1		0		0
Intersegment Eliminations [Member] | West [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues(1)	100		70		262		184
Intersegment Eliminations [Member] | Texas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues(1)	348		276		559		209
Intersegment Eliminations [Member] | East [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues(1)	228		18		365		133
Intersegment Eliminations [Member] | Retail [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues(1)	1		1		4		2
Other Assets [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Amortization of Intangible Assets	$ 18		$ 25		$ 39		$ 53
[1]	Includes intersegment revenues of $100 million and $70 million in the West, $348 million and $276 million in Texas, $228 million and $18 million in the East and $1 million and $1 million in Retail for the three months ended June 30, 2019 and 2018, respectively.
[2]	Includes intersegment revenues of $262 million and $184 million in the West, $559 million and $209 million in Texas, $365 million and $133 million in the East and $4 million and $2 million in Retail for the six months ended June 30, 2019 and 2018, respectively.
[3]	Includes $(19) million and $(19) million of lease levelization and $18 million and $25 million of amortization expense for the three months ended June 30, 2019 and 2018, respectively.
[4]	Includes $(35) million and $(35) million of lease levelization and $39 million and $53 million of amortization expense for the six months ended June 30, 2019 and 2018, respectively.