Employee Retirement Plans - Pension Plans Assets (Details) - Pension Benefits - U.S.	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans
Actual	100.00%	100.00%
Target Asset Allocation	100.00%	100.00%
Total domestic equity investments
Defined Benefit Plans and Other Postretirement Benefit Plans
Actual	26.50%	54.80%
Target Asset Allocation	29.00%	52.50%
Total domestic equity investments \| Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans
Target Asset Allocation	24.00%
Total domestic equity investments \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans
Target Asset Allocation	34.00%
International index equity mutual funds
Defined Benefit Plans and Other Postretirement Benefit Plans
Actual	25.00%	11.80%
Target Asset Allocation	24.50%	12.50%
International index equity mutual funds \| Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans
Target Asset Allocation	19.50%
International index equity mutual funds \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans
Target Asset Allocation	29.50%
Global equity index investments
Defined Benefit Plans and Other Postretirement Benefit Plans
Actual	12.30%	0.00%
Target Asset Allocation	11.50%	0.00%
Global equity index investments \| Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans
Target Asset Allocation	6.50%
Global equity index investments \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans
Target Asset Allocation	16.50%
Equity investments
Defined Benefit Plans and Other Postretirement Benefit Plans
Actual	63.80%	66.60%
Target Asset Allocation	65.00%	65.00%
Equity investments \| Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans
Target Asset Allocation	60.00%
Equity investments \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans
Target Asset Allocation	70.00%
Fixed income funds & cash equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Actual	36.20%	33.40%
Target Asset Allocation	35.00%	35.00%
Fixed income funds & cash equivalents \| Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans
Target Asset Allocation	30.00%
Fixed income funds & cash equivalents \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans
Target Asset Allocation	40.00%

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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+ References

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