Leases Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Lease Cost [Line Items]
Operating Lease, Cost	$ 16		$ 34
Short-term Lease, Cost	1		3
Variable Lease, Cost	4		9
Finance Lease, Right-of-Use Asset, Amortization	1		2
Sublease Income	(1)	$ 0	(3)	$ 0
Lease, Cost	21		45
Sublease Income	$ 1	$ 0	$ 3	$ 0

[Line Items] for Lease Cost [Table]

No definition available.

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- Definition

Amount of amortization expense attributable to right-of-use asset from finance lease.

+ References

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-Publisher FASB
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- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
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- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
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- Definition

Amount of short-term lease cost, excluding expense for lease with term of one month or less.

+ References

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- Definition

Amount of sublease income excluding finance and operating lease expense.

+ References

+ Details

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- Definition

Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

+ References

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