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Revenue Recognition - Disaggregated Revenues (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Mar. 31, 2019 | Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | $ 7,991 | $ 8,148 |
Mark-to-market for economic hedging activities |  |  |  |  |  |  |  |  | (20) | 14 | $ 206
Revenues | $ 2,195 | $ 2,996 | $ 2,465 | $ 2,165 | $ 1,992 | $ 2,960 | $ 2,461 | $ 2,065 | 9,821 | 9,478 | 9,074
Less: Lease revenue |  |  |  |  |  |  |  |  | 20 | 21 |
Derivative revenue |  |  |  |  |  |  |  |  | 0 | 31 | 195
Energy revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 1,222 | 1,548 |
Derivative revenue |  |  |  |  |  |  |  |  | 1,649 | 1,284 |
Capacity revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 607 | 670 |
Derivative revenue |  |  |  |  |  |  |  |  | 108 | 138 |
Retail Revenue | Mass customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 6,273 | 5,613 |
Retail Revenue | Business Solutions customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 1,403 | 1,492 |
Total retail revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 7,676 | 7,105 |
Derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Mark-to-market for economic hedging activities |  |  |  |  |  |  |  |  | 33 | (130) |
Derivative revenue |  |  |  |  |  |  |  |  | 1,810 | 1,309 |
Other revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 283 | 285 |
Total operating revenues |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  |  | 9,478 |
Revenues |  |  |  |  |  |  |  |  | 9,821 |  |
Other derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative revenue |  |  |  |  |  |  |  |  | 19 | 16 |
Corporate/Eliminations |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | (7) | (31) |
Revenues |  |  |  |  |  |  |  |  | (1,706) | (1,068) | (923)
Less: Lease revenue |  |  |  |  |  |  |  |  | 0 | 0 |
Corporate/Eliminations | Energy revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | (1,498) | (1,129) |
Derivative revenue |  |  |  |  |  |  |  |  | (1,499) | (1,117) |
Corporate/Eliminations | Capacity revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 1 | 0 |
Derivative revenue |  |  |  |  |  |  |  |  | 1 | 0 |
Corporate/Eliminations | Retail Revenue | Mass customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | (4) | (5) |
Corporate/Eliminations | Retail Revenue | Business Solutions customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Corporate/Eliminations | Total retail revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | (4) | (5) |
Corporate/Eliminations | Derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Mark-to-market for economic hedging activities |  |  |  |  |  |  |  |  | (201) | 79 |
Derivative revenue |  |  |  |  |  |  |  |  | (1,699) | (1,037) |
Corporate/Eliminations | Other revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | (4) | (13) |
Corporate/Eliminations | Total operating revenues |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  |  | (1,068) |
Revenues |  |  |  |  |  |  |  |  | (1,706) |  |
Corporate/Eliminations | Other derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative revenue |  |  |  |  |  |  |  |  | (1) | 0 |
Retail | Operating Segments |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 7,668 | 7,097 |
Revenues |  |  |  |  |  |  |  |  | 7,680 | 7,103 | 6,369
Less: Lease revenue |  |  |  |  |  |  |  |  | 12 | 13 |
Retail | Operating Segments | Energy revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Derivative revenue |  |  |  |  |  |  |  |  | 0 | 0 |
Retail | Operating Segments | Capacity revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Derivative revenue |  |  |  |  |  |  |  |  | 0 | 0 |
Retail | Operating Segments | Retail Revenue | Mass customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 6,277 | 5,618 |
Retail | Operating Segments | Retail Revenue | Business Solutions customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 1,403 | 1,492 |
Retail | Operating Segments | Total retail revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 7,680 | 7,110 |
Retail | Operating Segments | Derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Mark-to-market for economic hedging activities |  |  |  |  |  |  |  |  | 0 | (7) |
Derivative revenue |  |  |  |  |  |  |  |  | 0 | (7) |
Retail | Operating Segments | Other revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Lease revenue included in other revenue |  |  |  |  |  |  |  |  |  | 17 |
Retail | Operating Segments | Total operating revenues |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  |  | 7,103 |
Revenues |  |  |  |  |  |  |  |  | 7,680 |  |
Retail | Operating Segments | Other derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative revenue |  |  |  |  |  |  |  |  | 0 | 0 |
Retail | Corporate/Eliminations |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  | (10) | (9) | (4)
Generation | Operating Segments |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 330 | 1,082 |
Revenues |  |  |  |  |  |  |  |  | 3,847 | 3,443 | 3,615
Less: Lease revenue |  |  |  |  |  |  |  |  | 8 | 8 |
Generation | Operating Segments | Energy revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 2,720 | 2,677 |
Derivative revenue |  |  |  |  |  |  |  |  | 3,148 | 2,401 |
Generation | Operating Segments | Capacity revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 606 | 670 |
Derivative revenue |  |  |  |  |  |  |  |  | 107 | 138 |
Generation | Operating Segments | Retail Revenue | Mass customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | Retail Revenue | Business Solutions customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | Total retail revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | Derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Mark-to-market for economic hedging activities |  |  |  |  |  |  |  |  | 234 | (202) |
Derivative revenue |  |  |  |  |  |  |  |  | 3,509 | 2,353 |
Generation | Operating Segments | Other revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 287 | 298 |
Generation | Operating Segments | Total operating revenues |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  | 3,847 | 3,443 |
Generation | Operating Segments | Other derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative revenue |  |  |  |  |  |  |  |  | 20 | 16 |
Generation | Operating Segments | Texas |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | (870) | (664) |
Less: Lease revenue |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | Texas | Energy revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 1,987 | 1,585 |
Derivative revenue |  |  |  |  |  |  |  |  | 2,917 | 2,332 |
Generation | Operating Segments | Texas | Capacity revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 1 |
Derivative revenue |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | Texas | Retail Revenue | Mass customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | Texas | Retail Revenue | Business Solutions customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | Texas | Total retail revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | Texas | Derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Mark-to-market for economic hedging activities |  |  |  |  |  |  |  |  | 198 | (174) |
Derivative revenue |  |  |  |  |  |  |  |  | 3,145 | 2,160 |
Generation | Operating Segments | Texas | Other revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 90 | 84 |
Generation | Operating Segments | Texas | Total operating revenues |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  |  | 1,496 |
Revenues |  |  |  |  |  |  |  |  | 2,275 |  |
Generation | Operating Segments | Texas | Other derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative revenue |  |  |  |  |  |  |  |  | 30 | 2 |
Generation | Operating Segments | East/West Other |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 1,200 | 1,746 |
Less: Lease revenue |  |  |  |  |  |  |  |  | 8 | 8 |
Generation | Operating Segments | East/West Other | Energy revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 733 | 1,092 |
Derivative revenue |  |  |  |  |  |  |  |  | 231 | 69 |
Generation | Operating Segments | East/West Other | Capacity revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 606 | 669 |
Derivative revenue |  |  |  |  |  |  |  |  | 107 | 138 |
Generation | Operating Segments | East/West Other | Retail Revenue | Mass customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | East/West Other | Retail Revenue | Business Solutions customers |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | East/West Other | Total retail revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 0 | 0 |
Generation | Operating Segments | East/West Other | Derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Mark-to-market for economic hedging activities |  |  |  |  |  |  |  |  | 36 | (28) |
Derivative revenue |  |  |  |  |  |  |  |  | 364 | 193 |
Generation | Operating Segments | East/West Other | Other revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  | 197 | 214 |
Lease revenue included in other revenue |  |  |  |  |  |  |  |  |  | 5 |
Generation | Operating Segments | East/West Other | Total operating revenues |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from contract with customer |  |  |  |  |  |  |  |  |  | 1,947 |
Revenues |  |  |  |  |  |  |  |  | 1,572 |  |
Generation | Operating Segments | East/West Other | Other derivative revenue |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative revenue |  |  |  |  |  |  |  |  | (10) | 14 |
Generation | Corporate/Eliminations |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  | $ (1,602) | $ (1,085) | $ (877)

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- Definition Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919372-209981 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=77888421&loc=SL77919311-209978 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 50 -Paragraph 6A -URI http://asc.fasb.org/extlink&oid=118952077&loc=SL77927221-108306 + Details
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- Definition The total amount of revenue recognized for the period from operating leases, including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=77902458&loc=d3e39896-112707 + Details
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