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v3.20.1

Risk Management Activities (Narrative) (Details) - USD ($) | 3 Months Ended
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Mar. 31, 2020 | Mar. 31, 2019
Derivative [Line Items] |  |
Limit of GCA Volumes | 20.00% |
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net | $ 0 | $ 0
Interest Rate Swap |  |
Derivative [Line Items] |  |
Derivative, Notional Amount | $ 500,000,000.0 |
Minimum |  |
Derivative [Line Items] |  |
Commodity Contract Length | 5 years |
Maximum |  |
Derivative [Line Items] |  |
Commodity Contract Length | 10 years |

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