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Common Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Schedule of Common Equity [Line Items] |  |  |
Shares available for issuance under the 2020 OIP, Shareowner Direct Plan and 401(k) Savings Plan (in shares) | 15,000,000 |  |
Proceeds from issuance of common stock, net | $ 247 | $ 390 | $ 197
Equity Forward Agreements [Member] |  |  |
Schedule of Common Equity [Line Items] |  |  |
Common stock issued during the period (in shares) | 4,275,127 | 8,358,973 | 0
Proceeds from issuance of common stock, net | $ 222 | $ 366 |
Initial forward sale price (in dollars per share) | $ 51.98 | $ 43.75 |
At-the-market Offering Program [Member] |  |  |
Schedule of Common Equity [Line Items] |  |  |
Common stock issued during the period (in shares) | 0 | 0 | 4,171,013
Proceeds from issuance of common stock, net |  |  | $ 173
Maximum aggregate gross sales price of common stock that can be offered and sold |  |  | 175
Fees and commissions from issuance of common stock |  |  | $ 2

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