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v3.20.2

Fair Value Measurements - Level 3 Rollforward (Details) - Level 3 - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2020 | Dec. 31, 2019
NUG contracts |  |
Reconciliation of changes in the fair value of FTRs contracts |  |
Beginning Balance, Derivative Assets | $ 0 | $ 0
Beginning Balance, Derivative Liabilities | (16) | (44)
Beginning Balance, Net | (16) | (44)
Unrealized gain (loss), Derivative Assets | 0 | 0
Unrealized loss, Derivative Liabilities | (3) | (11)
Unrealized loss, Net | (3) | (11)
Purchases, Derivative Assets | 0 | 0
Purchases, Derivative Liabilities | 0 | 0
Purchases, Net | 0 | 0
Settlements, Derivative Assets | 0 | 0
Settlements, Derivative Liabilities | 19 | 39
Settlements, Net | 19 | 39
Ending Balance, Derivative Assets | 0 | 0
Ending Balance, Derivative Liabilities | 0 | (16)
Ending Balance, Net | 0 | (16)
FTRs |  |
Reconciliation of changes in the fair value of FTRs contracts |  |
Beginning Balance, Derivative Assets | 4 | 10
Beginning Balance, Derivative Liabilities | (1) | (1)
Beginning Balance, Net | 3 | 9
Unrealized gain (loss), Derivative Assets | 0 | (1)
Unrealized loss, Derivative Liabilities | 0 | 0
Unrealized loss, Net | 0 | (1)
Purchases, Derivative Assets | 7 | 6
Purchases, Derivative Liabilities | (2) | (4)
Purchases, Net | 5 | 2
Settlements, Derivative Assets | (4) | (11)
Settlements, Derivative Liabilities | 3 | 4
Settlements, Net | (1) | (7)
Ending Balance, Derivative Assets | 7 | 4
Ending Balance, Derivative Liabilities | 0 | (1)
Ending Balance, Net | $ 7 | $ 3

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