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v3.22.2.2

Derivative Financial Instruments (Derivative Instruments Carrying Value) (Detail) - Not Designated As Hedging Instrument - USD ($) $ in Millions | Sep. 30, 2022 | Dec. 31, 2021
--- | --- | ---
Derivative [Line Items] |  |
Derivative assets | $ 167 | $ 90
Derivative Liability | 177 | 202
Fuel oils | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 12 | 8
Fuel oils | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 3 | 5
Fuel oils | Other deferred credits and liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 1 | 0
Natural gas | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 71 | 35
Natural gas | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 34 | 18
Natural gas | Other deferred credits and liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 4 | 3
Natural gas | Other current liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 11 | 8
Power | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 39 | 23
Power | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 5 | 0
Power | Other deferred credits and liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 50 | 131
Power | Other current liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 111 | 59
Uranium | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 2 | 0
Uranium | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 1 | 1
Uranium | Other current liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 0 | 1
Union Electric Company |  |
Derivative [Line Items] |  |
Derivative assets | 73 | 49
Derivative Liability | 129 | 77
Union Electric Company | Fuel oils | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 12 | 8
Union Electric Company | Fuel oils | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 3 | 5
Union Electric Company | Fuel oils | Other deferred credits and liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 1 | 0
Union Electric Company | Natural gas | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 14 | 7
Union Electric Company | Natural gas | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 13 | 5
Union Electric Company | Natural gas | Other deferred credits and liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 1 | 1
Union Electric Company | Natural gas | Mark-to-market derivative liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 2 | 2
Union Electric Company | Natural gas | Other current liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 0 | 0
Union Electric Company | Power | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 28 | 23
Union Electric Company | Power | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 0 | 0
Union Electric Company | Power | Other deferred credits and liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 14 | 23
Union Electric Company | Power | Mark-to-market derivative liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 111 | 50
Union Electric Company | Power | Other current liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 0 | 0
Union Electric Company | Uranium | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 2 | 0
Union Electric Company | Uranium | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 1 | 1
Union Electric Company | Uranium | Mark-to-market derivative liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 0 | 1
Union Electric Company | Uranium | Other current liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 0 | 0
Ameren Illinois Company |  |
Derivative [Line Items] |  |
Derivative assets | 94 | 41
Derivative Liability | 48 | 125
Ameren Illinois Company | Fuel oils | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 0 | 0
Ameren Illinois Company | Fuel oils | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 0 | 0
Ameren Illinois Company | Fuel oils | Other deferred credits and liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 0 | 0
Ameren Illinois Company | Natural gas | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 0 | 0
Ameren Illinois Company | Natural gas | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 21 | 13
Ameren Illinois Company | Natural gas | Mark-to-market derivative assets |  |
Derivative [Line Items] |  |
Derivative assets | 57 | 28
Ameren Illinois Company | Natural gas | Other deferred credits and liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 3 | 2
Ameren Illinois Company | Natural gas | Other current liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 9 | 6
Ameren Illinois Company | Power | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 0 | 0
Ameren Illinois Company | Power | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 5 | 0
Ameren Illinois Company | Power | Mark-to-market derivative assets |  |
Derivative [Line Items] |  |
Derivative assets | 11 | 0
Ameren Illinois Company | Power | Other deferred credits and liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 36 | 108
Ameren Illinois Company | Power | Other current liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | 0 | 9
Ameren Illinois Company | Uranium | Other current assets |  |
Derivative [Line Items] |  |
Derivative assets | 0 | 0
Ameren Illinois Company | Uranium | Other assets |  |
Derivative [Line Items] |  |
Derivative assets | 0 | 0
Ameren Illinois Company | Uranium | Other current liabilities |  |
Derivative [Line Items] |  |
Derivative Liability | $ 0 | $ 0

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