Leases - Supplemental Cash Flow Information (Details) $ in Millions	6 Months Ended
Mar. 31, 2020 USD ($)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 9
Operating cash flows from finance leases	0
Financing cash flows from finance leases	1
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	6
Finance leases	$ 2

Cash Flow Lessee [Abstract]

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- Definition

Right of Use Assets Obtained in Exchange For Lease Liabilities [Abstract]

+ References

No definition available.

+ Details

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- Definition

Amount of interest paid on finance lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(1)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918643-209977

+ Details

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- Definition

Amount of cash outflow for principal payment on finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 5
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-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918643-209977

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-Publisher FASB
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-Section 50
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+ Details

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- Definition

Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918643-209977

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-Publisher FASB
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- Definition

Amount of increase in right-of-use asset obtained in exchange for finance lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
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- Definition

Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

+ References

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