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Accounting Policies (Narrative) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2018 USD ($)
Accounting Policies [Abstract] |
Investment tax credit | $ 13

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- Definition The amount deducted from an entities' taxes, reflecting a percentage of an amount invested in certain assets spread over the useful life of those assets; includes deferred investment tax credits. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
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