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Common Equity (Common Share Activity) (Details) - shares | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Common Stock Oustanding [Roll Forward] |  |  |
Shares outstanding, January 1 (in shares) | 245,022,800 | 236,063,279 | 231,348,646
Common stock issued during the period, Shareowner Direct Plan (in shares) | 472,283 | 501,808 | 576,965
Common stock issued during the period, Equity-based compensation plans (in shares) | 98,205 | 101,478 | 5,078
Common stock issued during the period, Other (in shares) | 0 | (2,738) | (38,423)
Shares outstanding, December 31 (in shares) | 249,868,415 | 245,022,800 | 236,063,279
Equity Forward Agreements [Member] |  |  |
Common Stock Oustanding [Roll Forward] |  |  |
Common stock issued during the period (in shares) | 4,275,127 | 8,358,973 | 0
At-the-market Offering Program [Member] |  |  |
Common Stock Oustanding [Roll Forward] |  |  |
Common stock issued during the period (in shares) | 0 | 0 | 4,171,013

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