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Fair Value Measurements Fair Value Measurements - Investments (Details) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Jun. 30, 2019 USD ($) | Jun. 30, 2018 USD ($) | Jun. 30, 2019 USD ($) | Jun. 30, 2018 USD ($) | Sep. 30, 2018 USD ($)
Investment Gains (Losses) |  |  |  |  |
Financing Receivable, after Allowance for Credit Loss | $ 111 |  | $ 111 |  | $ 123
Balance in NDT | 2,100 |  | 2,100 |  |
Balance in ART | $ 717 |  | $ 717 |  |
Period of time where the investor contributes capital to an investment in a private partnership - minimum |  |  | three |  |
Period of time where the investor contributes capital to an investment in a private partnership - maximum |  |  | four |  |
Minimum investment period |  |  | 10 years |  |
Number of readily available quoted exchange prices for the investments | 0 |  | 0 |  |
SERP |  |  |  |  |
Investment Gains (Losses) |  |  |  |  |
Unrealized gains (losses) on investments | $ 1 | $ 0 | $ 0 | $ 0 |
DCP |  |  |  |  |
Investment Gains (Losses) |  |  |  |  |
Unrealized gains (losses) on investments | 1 | 0 | (1) | 0 |
NDT |  |  |  |  |
Investment Gains (Losses) |  |  |  |  |
Unrealized gains (losses) on investments | (37) | 9 | (84) | (19) |
ART |  |  |  |  |
Investment Gains (Losses) |  |  |  |  |
Unrealized gains (losses) on investments | (6) | $ 1 | (58) | $ 7 |
Equity Funds |  |  |  |  |
Investment Gains (Losses) |  |  |  |  |
NDT unfunded commitments related to private equity and real estate | 185 |  | 185 |  |
Real Estate Funds |  |  |  |  |
Investment Gains (Losses) |  |  |  |  |
NDT unfunded commitments related to private equity and real estate | 35 |  | 35 |  |
Credit [Member] |  |  |  |  |
Investment Gains (Losses) |  |  |  |  |
NDT unfunded commitments related to private equity and real estate | 4 |  | 4 |  |
Private Equity Funds [Member] |  |  |  |  |
Investment Gains (Losses) |  |  |  |  |
NDT unfunded commitments related to private equity and real estate | 95 |  | 95 |  |
Private real estate funds [Member] |  |  |  |  |
Investment Gains (Losses) |  |  |  |  |
Fair value plan assets gross | 16 |  | 16 |  |
Private Credit [Member] |  |  |  |  |
Investment Gains (Losses) |  |  |  |  |
NDT unfunded commitments related to private equity and real estate | $ 2 |  | $ 2 |  |

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- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. This amount is not reduced by non-benefit liabilities. + References No definition available. + Details
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- Definition Fair value portion of arrangements with third parties, including, but not limited to, operating lease arrangement and arrangement in which the entity has agreed to expend funds to procure goods or services, or has agreed to commit resources to supply goods or services. + 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(25)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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