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v3.19.1

Fair Value Measurements (Details 1) - Level 3 - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2019 | Dec. 31, 2017
NUG contracts |  |
Reconciliation of changes in the fair value of FTRs contracts |  |
Beginning Balance, Derivative Assets | $ 0 |
Beginning Balance, Derivative Liabilities | (44) |
Beginning Balance, Net | (44) |
Unrealized gain (loss), Derivative Assets | 0 | $ 0
Unrealized loss, Derivative Liabilities | (7) | 2
Unrealized loss, Net | (7) | 2
Purchases, Derivative Assets | 0 | 0
Purchases, Derivative Liabilities | 0 | 0
Purchases, Net | 0 | 0
Settlements, Derivative Assets | 0 | 0
Settlements, Derivative Liabilities | 10 | 33
Settlements, Net | 10 | 33
Ending Balance, Derivative Assets | 0 | 0
Ending Balance, Derivative Liabilities | (41) | (79)
Ending Balance, Net | (41) | (79)
FTRs |  |
Reconciliation of changes in the fair value of FTRs contracts |  |
Beginning Balance, Derivative Assets | 10 |
Beginning Balance, Derivative Liabilities | (1) |
Beginning Balance, Net | 9 |
Unrealized gain (loss), Derivative Assets | 0 | 8
Unrealized loss, Derivative Liabilities | 0 | 1
Unrealized loss, Net | 0 | 9
Purchases, Derivative Assets | 0 | 5
Purchases, Derivative Liabilities | 0 | (5)
Purchases, Net | 0 | 0
Settlements, Derivative Assets | (10) | (6)
Settlements, Derivative Liabilities | 0 | 3
Settlements, Net | (10) | (3)
Ending Balance, Derivative Assets | 0 | 3
Ending Balance, Derivative Liabilities | (1) | 0
Ending Balance, Net | $ (1) | $ 3

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