Retirement Benefit Plans - Asset Allocation Ranges of Defined Benefit Plan Investments (Details)	12 Months Ended
Sep. 30, 2016	Sep. 30, 2015
Asset Allocation Range provides flexibility for the Plan's investments
Total	100.00%	100.00%
U.S. equities
Asset Allocation Range provides flexibility for the Plan's investments
Total	50.00%	50.00%
Asset Allocations Range Minimum	30.00%
Asset Allocations Range Maximum	70.00%
Non-U.S. equities
Asset Allocation Range provides flexibility for the Plan's investments
Total	7.00%	8.00%
Asset Allocations Range Minimum	0.00%
Asset Allocations Range Maximum	20.00%
U.S. debt securities
Asset Allocation Range provides flexibility for the Plan's investments
Total	41.00%	40.00%
Asset Allocations Range Minimum	20.00%
Asset Allocations Range Maximum	70.00%
Non-U.S. debt securities
Asset Allocation Range provides flexibility for the Plan's investments
Total	0.00%	0.00%
Asset Allocations Range Minimum	0.00%
Asset Allocations Range Maximum	10.00%
Other securities
Asset Allocation Range provides flexibility for the Plan's investments
Total	2.00%	2.00%
Asset Allocations Range Minimum	0.00%
Asset Allocations Range Maximum	60.00%

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Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

Target allocation minimum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920

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- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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