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Share capital - Rio Tinto Limited - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Classes Of Share Capital [Line Items]
Rio Tinto Limited shares were held by Rio Tinto plc	0	0	0
Rio Tinto Limited [member]
Disclosure Of Classes Of Share Capital [Line Items]
Value of shares purchased by employee share ownership trusts	$ 114.0	$ 37.5	$ 48.5
Rio Tinto Limited shares were held by Rio Tinto plc	1,416,728

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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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- Definition

The number of shares in the entity held by the entity or by its subsidiaries or associates. [Refer: Associates [member]; Subsidiaries [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 79
-Subparagraph a
-Clause vi
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_79_a_vi&doctype=Standard
-URIDate 2017-03-09

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- Definition

Value of shares purchased by employee share ownership trusts.

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