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Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Sep. 30, 2019
Fair Value of Financial Instruments [Line Items] |  |
Investment excludes receivables, payables and accrued income | $ 4 | $ (15)
Cash balance excluded from available for sale securities | 20 | 33
Investments not required to be disclosed | 253 | 283
Nuclear plant decommissioning trusts | $ 790 | 871
NUG contracts |  |
Fair Value of Financial Instruments [Line Items] |  |
Period of future observable data to determine contract price | 2 years |
Nuclear Plant Matters | JCP&L, ME and PN | Financial Guarantee |  |
Fair Value of Financial Instruments [Line Items] |  |
Nuclear plant decommissioning trusts |  | $ 900

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- Definition Decommission fund to pay for the costs of decontaminating and decommissioning of facilities through collection of revenues derived from utility assessments and government appropriations. Decommission fund investment for the process whereby a power station, at the end of its economic life, is taken permanently out of service and its site made available for other purposes. In the case of a nuclear station this comprises three different states of clearance. Immediately after the final closure, radioactive material such as nuclear fuel and operational waste is removed and the buildings surrounding the reactor shield are dismantled and finally the reactor itself is dismantled. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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