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Revenue Recognition Revenue Recognition (Allowance for Credit Losses) (Details) - USD ($) $ in Millions | 6 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jun. 30, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |
Allowance for Credit Loss | $ 41.6 | $ 52.3 | $ 13.0
Current period provisions | 5.5 | 54.6 |
Write-offs charged against allowance | (23.2) | (29.7) |
Recoveries of amounts previously written off | 7.0 | 14.4 |
Gas Distribution Operations |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |
Allowance for Credit Loss | 35.4 | 41.8 | 9.1
Current period provisions | 5.1 | 45.3 |
Write-offs charged against allowance | (18.3) | (26.7) |
Recoveries of amounts previously written off | 6.8 | 14.1 |
Electric Operations |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |
Allowance for Credit Loss | 5.4 | 9.7 | 3.1
Current period provisions | 0.4 | 9.3 |
Write-offs charged against allowance | (4.9) | (3.0) |
Recoveries of amounts previously written off | 0.2 | 0.3 |
Corporate and Other |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |
Allowance for Credit Loss | 0.8 | 0.8 | $ 0.8
Current period provisions | 0.0 | 0.0 |
Write-offs charged against allowance | 0.0 | 0.0 |
Recoveries of amounts previously written off | $ 0.0 | $ 0.0 |

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