Investments Accounted for Using the Equity Method - Summary of Ownership Interest in Equity Accounted Investments (Detail)	12 Months Ended
Jun. 30, 2020	Jun. 30, 2019
Disclosure of significant investments in associates and joint ventures [line items]
Reporting date	--06-30
Samarco Mineracao S.A. [member]
Disclosure of significant investments in associates and joint ventures [line items]
Country of incorporation	Brazil
Principal place of business	Brazil
Principal activity	Iron ore mining
Reporting date	--12-31
Ownership interest	50.00%	50.00%
Carbones del Cerrejon LLC [member]
Disclosure of significant investments in associates and joint ventures [line items]
Country of incorporation	Anguilla
Principal place of business	Colombia/Ireland
Principal activity	Coal mining in Colombia
Reporting date	--12-31
Ownership interest	33.33%	33.33%
Compania Minera Antamina S.A. [member]
Disclosure of significant investments in associates and joint ventures [line items]
Country of incorporation	Peru
Principal place of business	Peru
Principal activity	Copper and zinc mining
Reporting date	--12-31
Ownership interest	33.75%	33.75%

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End date of current fiscal year in the format --MM-DD.

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The country in which a joint venture of the entity is incorporated. [Refer: Joint ventures [member]]

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The country in which an associate of the entity is incorporated. [Refer: Associates [member]]

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The description of the nature of the entity's operations and principal activities.

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The principal place of business of an associate. [Refer: Principal place of business; Associates [member]]

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The proportion of ownership interest in an associate attributable to the entity. [Refer: Associates [member]]

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