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Share capital - Summary of share capital (Detail) - Rio Tinto plc [member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2015
Disclosure Of Classes Of Share Capital [Line Items]
Issued and fully paid up share capital at beginning balance	$ 224	$ 230
Shares purchased and cancelled	(4)	(6)
Issued and fully paid up share capital at ending balance	$ 220	$ 224

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- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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No definition available.

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- Definition

The nominal value of capital issued.

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- Definition

The decrease in equity resulting from a reduction in issued capital. [Refer: Issued capital]

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