Pension and Postretirement Plans - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2023	Mar. 31, 2023
Retirement Benefits [Abstract]
Net actuarial gain (loss)	$ (15)	$ (23)

Amount of gain (loss), recognized immediately as component of net periodic benefit (cost) credit, for change in value of benefit obligation or plan assets from experience different from that assumed, change in actuarial assumption, or consequence of temporarily deviating from substantive plan. Includes, but is not limited to, amount in excess of 10 percent of greater of fair value of plan assets or benefit obligation.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 3A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480535/715-20-45-3A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (h)(4)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(4)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-6

Name:	us-gaap_DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration