Subsequent Events - Additional Information (Detail) - Kwinana Refinery [Member] MT in Millions, $ in Millions		3 Months Ended
	Jan. 08, 2024 Employee MT	Mar. 31, 2024 USD ($)	Sep. 30, 2025 Employee	Sep. 30, 2024 Employee
Scenario Forecast [Member]
Subsequent Event [Line Items]
Number of employees | Employee			50	250
Cash outlays spent in 2023		$ 115
Cash outlays expected in 2024		80
Cash outlays expected in 2025		35
Scenario Forecast [Member] | Maximum [Member]
Subsequent Event [Line Items]
Restructuring charges		200
Scenario Forecast [Member] | Minimum [Member]
Subsequent Event [Line Items]
Restructuring charges		180
Scenario Forecast [Member] | Water Management Costs [Member]
Subsequent Event [Line Items]
Restructuring charges		81
Scenario Forecast [Member] | Employee Related Costs [Member]
Subsequent Event [Line Items]
Restructuring charges		55
Scenario Forecast [Member] | Asset Retirement Obligations [Member]
Subsequent Event [Line Items]
Restructuring charges		26
Scenario Forecast [Member] | Other Costs [Member]
Subsequent Event [Line Items]
Restructuring charges		$ 18
Subsequent Event [Member]
Subsequent Event [Line Items]
Number of employees | Employee	800
Percentage of operating production of annual capacity	80.00%
Annual capacity of production | MT	2.2