Fair Value Measurements - Summary of Financial Instruments Subject to Recurring Fair Value Measurements (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Millions		Sep. 30, 2022		Sep. 30, 2021
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Assets
Cash and cash equivalents		$ 646		$ 210
Restricted investments		374	[1],[2]	421	[3],[4]
Investments of captive insurance company		9	[5]	8	[6]
Foreign currency derivatives		1	[7]	1
Total assets at fair value		1,034		645
Liabilities
Foreign currency derivatives		9	[8]	2	[9]
Total liabilities at fair value		10
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Commodity Derivatives [Member]
Assets
Commodity derivatives		$ 4	[7]	$ 5	[10]
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Accounts Receivable, after Allowance for Credit Loss, Current		Accounts Receivable, after Allowance for Credit Loss, Current
Liabilities
Commodity derivatives	[8]	$ 1
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Accrued Liabilities, Current
Estimate of Fair Value, Fair Value Disclosure [Member]
Assets
Cash and cash equivalents		$ 646		$ 210
Restricted investments		374	[1],[2]	421	[3],[4]
Investments of captive insurance company		9	[5]	8	[6]
Foreign currency derivatives		1	[7]	1
Total assets at fair value		1,034		645
Liabilities
Foreign currency derivatives		9	[8]	2	[9]
Total liabilities at fair value		10
Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity Derivatives [Member]
Assets
Commodity derivatives		$ 4	[7]	$ 5	[10]
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Accounts Receivable, after Allowance for Credit Loss, Current		Accounts Receivable, after Allowance for Credit Loss, Current
Liabilities
Commodity derivatives	[8]	$ 1
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Accrued Liabilities, Current
Fair Value, Inputs, Level 1 [Member]
Assets
Cash and cash equivalents		$ 646		$ 210
Restricted investments		374	[1],[2]	421	[3],[4]
Investments of captive insurance company		9	[5]	8	[6]
Foreign currency derivatives		0	[7]	0
Total assets at fair value		1,029		639
Liabilities
Foreign currency derivatives		0	[8]	0	[9]
Total liabilities at fair value		0
Fair Value, Inputs, Level 1 [Member] | Commodity Derivatives [Member]
Assets
Commodity derivatives		0	[7]	0	[10]
Liabilities
Commodity derivatives	[8]	0
Fair Value, Inputs, Level 2 [Member]
Assets
Cash and cash equivalents		0		0
Restricted investments		0	[1],[2]	0	[3],[4]
Investments of captive insurance company		0	[5]	0	[6]
Foreign currency derivatives		1	[7]	1
Total assets at fair value		5		6
Liabilities
Foreign currency derivatives		9	[8]	2	[9]
Total liabilities at fair value		10
Fair Value, Inputs, Level 2 [Member] | Commodity Derivatives [Member]
Assets
Commodity derivatives		4	[7]	5	[10]
Liabilities
Commodity derivatives	[8]	1
Fair Value, Inputs, Level 3 [Member]
Assets
Cash and cash equivalents		0		0
Restricted investments		0	[1],[2]	0	[3],[4]
Investments of captive insurance company		0	[5]	0	[6]
Foreign currency derivatives		0	[7]	0
Total assets at fair value		0		0
Liabilities
Foreign currency derivatives		0	[8]	0	[9]
Total liabilities at fair value		0
Fair Value, Inputs, Level 3 [Member] | Commodity Derivatives [Member]
Assets
Commodity derivatives		0	[7]	$ 0	[10]
Liabilities
Commodity derivatives	[8]	$ 0

[1] Included in restricted investments and $61 million within other current assets in the Consolidated Balance Sheets.

[2] Includes $245 million related to the Asbestos trust and $129 million related to the Environmental trust. See Note A for additional details.

[3] Included in restricted investments and $37 million within other current assets in the Consolidated Balance Sheets.

[4] Includes $333 million related to the Asbestos trust and $88 million related to the Environmental trust. See Note A for additional details.

[5] Included in other noncurrent assets in the Consolidated Balance Sheets.

[6] Included in other noncurrent assets in the Consolidated Balance Sheets.

[7] Included in accounts receivable in the Consolidated Balance Sheets.

[8] Included in accrued expenses and other liabilities in the Consolidated Balance Sheets.

[9] Included in accrued expenses and other liabilities in the Consolidated Balance Sheets.

[10] Included in accounts receivable in the Consolidated Balance Sheets.