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Benefit Plans Components of Benefit Plans (Details) - USD ($) | 12 Months Ended
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Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2018
Defined Benefit Plan Disclosure |  |  |
Fixed and variable fund annual maximum contribution |  | $ 10,000 |
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Assets Transferred to (from) Plan |  | 23,000,000 |
Defined contribution plan contribution amount | $ 88,000,000 | $ 84,000,000 | $ 80,000,000
Minimum |  |  |
Defined Benefit Plan Disclosure |  |  |
Threshold for Deferral of Actuarial Gain/Loss Under Corridor Approach |  | 10.00% |

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- Definition The maximum annual contribution that employees can make to the fixed and variable fund benefit. The fixed fund benefit is a benefit that earns a specified rate of interest on contributions made by employees. The variable fund is a benefit that invests employee contributions in the Spartan U.S. Equity Index Fund-Fidelity Advantage Class (Spartan). + References No definition available. + Details
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- Definition Threshold for Deferral of Actuarial Gain/Loss Under Corridor Approach + References No definition available. + Details
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- Definition Amount of increase (decrease) in plan assets of defined benefit plan from assets transferred into (from) plan. + References No definition available. + Details
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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. + References No definition available. + Details
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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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- Details
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