CONTINGENCIES, COMMITMENTS, AND GUARANTEES - SO Other Matters (Details) $ in Millions	3 Months Ended
Dec. 31, 2019 USD ($)	Dec. 31, 2017 lessee
Commitments and Contingencies Disclosure [Abstract]
Number of lessees \| lessee		1
Lease, impairment loss	$ 17
Lease, impairment loss, after tax	13
Leveraged lease investment	$ 76

Carrying amount as of the balance sheet date of leveraged lease investments which represent the aggregate amount of the estimated residual value of the lease assets and lease payments receivables, net of unearned and deferred income to be allocated over the lease term and non-recourse debt.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(10))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 25
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=77899714&loc=d3e42229-112728

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(17))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=84165051&loc=d3e45424-112738

Name:	us-gaap_LeveragedLeaseInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant