Fair Value Measurements - Narrative (Details) - Private equity - Alabama Power - USD ($) $ in Millions |
Dec. 31, 2018 |
Dec. 31, 2017 |
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| Fair Value, Option, Quantitative Disclosures [Line Items] | ||
| Alternative investment | $ 45 | $ 29 |
| Unfunded commitments | $ 50 | $ 21 |
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- Definition Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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