| Fair Value, Measurement Inputs, Disclosure |
The following tables present our assets and liabilities that were accounted for at fair value on a recurring basis as of March 31, 2020 and December 31, 2019, by level within the fair value hierarchy: | | | | | | | | | | | | | | | | | | Assets and Liabilities with Recurring Fair Value Measures as of March 31, 2020 | | Level 1 | | Level 2 | | Level 3 | | Total | | (in millions) | Assets: | | | | | | | | Cash equivalents(1) | $ | 444 |
| | $ | — |
| | $ | — |
| | $ | 444 |
| Commodity instruments: | | | | | | | | Commodity exchange traded derivatives contracts | 1,198 |
| | — |
| | — |
| | 1,198 |
| Commodity forward contracts(2) | — |
| | 383 |
| | 366 |
| | 749 |
| Interest rate hedging instruments | — |
| | — |
| | — |
| | — |
| Effect of netting and allocation of collateral(3)(4) | (1,198 | ) | | (235 | ) | | (25 | ) | | (1,458 | ) | Total assets | $ | 444 |
| | $ | 148 |
| | $ | 341 |
| | $ | 933 |
| Liabilities: | | | | | | | | Commodity instruments: | | | | | | | | Commodity exchange traded derivatives contracts | $ | 1,233 |
| | $ | — |
| | $ | — |
| | $ | 1,233 |
| Commodity forward contracts(2) | — |
| | 379 |
| | 117 |
| | 496 |
| Interest rate hedging instruments | — |
| | 150 |
| | — |
| | 150 |
| Effect of netting and allocation of collateral(3)(4) | (1,233 | ) | | (243 | ) | | (25 | ) | | (1,501 | ) | Total liabilities | $ | — |
| | $ | 286 |
| | $ | 92 |
| | $ | 378 |
|
| | | | | | | | | | | | | | | | | | Assets and Liabilities with Recurring Fair Value Measures as of December 31, 2019 | | Level 1 | | Level 2 | | Level 3 | | Total | | (in millions) | Assets: | | | | | | | | Cash equivalents(1) | $ | 784 |
| | $ | — |
| | $ | — |
| | $ | 784 |
| Commodity instruments: | | | | | | | | Commodity exchange traded derivatives contracts | 872 |
| | — |
| | — |
| | 872 |
| Commodity forward contracts(2) | — |
| | 245 |
| | 294 |
| | 539 |
| Interest rate hedging instruments | — |
| | 12 |
| | — |
| | 12 |
| Effect of netting and allocation of collateral(3)(4) | (872 | ) | | (131 | ) | | (18 | ) | | (1,021 | ) | Total assets | $ | 784 |
| | $ | 126 |
| | $ | 276 |
| | $ | 1,186 |
| Liabilities: | | | | | | | | Commodity instruments: | | | | | | | | Commodity exchange traded derivatives contracts | $ | 984 |
| | $ | — |
| | $ | — |
| | $ | 984 |
| Commodity forward contracts(2) | — |
| | 285 |
| | 123 |
| | 408 |
| Interest rate hedging instruments | — |
| | 31 |
| | — |
| | 31 |
| Effect of netting and allocation of collateral(3)(4) | (984 | ) | | (133 | ) | | (18 | ) | | (1,135 | ) | Total liabilities | $ | — |
| | $ | 183 |
| | $ | 105 |
| | $ | 288 |
|
___________ | | (1) | At March 31, 2020 and December 31, 2019, we had cash equivalents of $222 million and $573 million included in cash and cash equivalents and $222 million and $211 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 6 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 $35 million, $8 million and nil, respectively, at March 31, 2020. Cash collateral posted with (received from) counterparties allocated to level 1, level 2 and level 3 derivative instruments totaled $112 million, $2 million and nil, respectively, at December 31, 2019. |
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| 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 March 31, 2020 and December 31, 2019: | | | | | | | | | | | | | | | | | | | | | | | Quantitative Information about Level 3 Fair Value Measurements | | | March 31, 2020 | | | Fair Value, Net Asset | | | | Significant Unobservable | | | | | | | | | | (Liability) | | Valuation Technique | | Input | | Range | | Average(2) | | | (in millions) | | | | | | | | | | | | Power Contracts(1) | | $ | 211 |
| | Discounted cash flow | | Market price (per MWh) | | $ | 3.47 |
| — | $159.64 | /MWh | | $ | 27.96 |
| Power Congestion Products | | $ | 11 |
| | Discounted cash flow | | Market price (per MWh) | | $ | (6.48 | ) | — | $42.00 | /MWh | | $ | 3.48 |
| Natural Gas Contracts | | $ | 10 |
| | Discounted cash flow | | Market price (per MMBtu) | | $ | 1.13 |
| — | $4.77 | /MMBtu | | $ | 2.60 |
| | | | | | | | | | | | | | | | | December 31, 2019 | | | Fair Value, Net Asset | | | | Significant Unobservable | | | | | | | | | | (Liability) | | Valuation Technique | | Input | | Range | | | | | (in millions) | | | | | | | | | | | | Power Contracts(1) | | $ | 158 |
| | Discounted cash flow | | Market price (per MWh) | | $ | 4.85 |
| — | $184.15 | /MWh | | | Power Congestion Products | | $ | 17 |
| | Discounted cash flow | | Market price (per MWh) | | $ | (10.32 | ) | — | $20 | /MWh | | | Natural Gas Contracts | | $ | (20 | ) | | Discounted cash flow | | Market price (per MMBtu) | | $ | 1.73 |
| — | $6.45 | /MMBtu | | |
___________ | | (1) | Power contracts include power and heat rate instruments classified as level 3 in the fair value hierarchy. |
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| 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 March 31, | | | 2020 | | 2019 | Balance, beginning of period | | $ | 171 |
| | $ | (8 | ) | Realized and mark-to-market gains (losses): | | | | | Included in net income: | | | | | Included in operating revenues(1) | | 81 |
| | 50 |
| Included in fuel and purchased energy expense(2) | | (4 | ) | | 2 |
| Change in collateral | | — |
| | 2 |
| Purchases, Issuances and settlements: | | | | | Purchases | | — |
| | 2 |
| Settlements | | — |
| | 58 |
| Transfers in and/or out of level 3: | | | | | Transfers into level 3(3) | | 3 |
| | (1 | ) | Transfers out of level 3(4) | | (2 | ) | | — |
| Balance, end of period | | $ | 249 |
| | $ | 105 |
| Change in unrealized gains (losses) included in net income relating to instruments still held at end of period | | $ | 77 |
| | $ | 52 |
|
___________ | | (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 $3 million in gains and $(1) million in losses transferred out of level 2 into level 3 for the three months ended March 31, 2020 and 2019, respectively, due to changes in market liquidity in various power markets. |
| | (4) | We had $2 million in gains and nil transferred out of level 3 into level 2 for the three months ended March 31, 2020 and 2019, respectively, due to changes in market liquidity in various power markets. |
|