Financial Risk Management - Foreign Exchange Risk (Details) R in Millions	12 Months Ended
Jun. 30, 2019 ZAR (R) USD_per_PGK R / $	Jun. 30, 2018 ZAR (R) USD_per_PGK R / $
Disclosure of nature and extent of risks arising from financial instruments [line items]
Foreign exchange rate risk hedged limit (as a percent)	25.00%
Foreign exchange risk exposure term	24 months
Currency risk
Disclosure of nature and extent of risks arising from financial instruments [line items]
Reasonably possible change in risk variable percent	10.00%	10.00%
Currency risk \| Financial assets \| US$ against Kina
Disclosure of nature and extent of risks arising from financial instruments [line items]
Risk exposure	R 211	R 30
Reasonably possible increase in risk variable percent	10.00%	10.00%
Increase by 10%, impact on earnings	R 19	R 3
Reasonably possible decrease in risk variable percent	10.00%	10.00%
Decrease by 10%, impact on earnings	R (23)	R (3)
Closing rate \| USD_per_PGK	0.30	0.30
Currency risk \| Derivative financial instruments \| Rand against US$
Disclosure of nature and extent of risks arising from financial instruments [line items]
Risk exposure	R 454	R (136)
Reasonably possible increase in risk variable percent	10.00%	10.00%
Increase by 10%, impact on earnings	R 567	R 666
Reasonably possible decrease in risk variable percent	10.00%	10.00%
Decrease by 10%, impact on earnings	R (1,511)	R (625)
Closing rate \| R / $	14.13	13.81
Currency risk \| Borrowings \| Rand against US$
Disclosure of nature and extent of risks arising from financial instruments [line items]
Risk exposure	R 4,143	R 5,114
Reasonably possible increase in risk variable percent	10.00%	10.00%
Increase by 10%, impact on earnings	R 414	R 511
Reasonably possible decrease in risk variable percent	10.00%	10.00%
Decrease by 10%, impact on earnings	R (414)	R (511)
Closing rate \| R / $	14.13	13.81
Currency risk \| Borrowings \| US$ against Kina
Disclosure of nature and extent of risks arising from financial instruments [line items]
Risk exposure	R 283	R 0
Reasonably possible increase in risk variable percent	10.00%	10.00%
Increase by 10%, impact on earnings	R 26	R 0
Reasonably possible decrease in risk variable percent	10.00%	10.00%
Decrease by 10%, impact on earnings	R (31)	R 0
Closing rate \| USD_per_PGK	0.30	0.30
Bottom of range \| Currency risk
Disclosure of nature and extent of risks arising from financial instruments [line items]
Reasonably possible change in risk variable percent	10.00%	10.00%
Top of range \| Currency risk
Disclosure of nature and extent of risks arising from financial instruments [line items]
Reasonably possible change in risk variable percent	20.00%	20.00%

Foreign Currency Exchange Notional Amount, Percentage Hedged Limit

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Foreign Exchange Risk Exposure Term

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Sensitivity Analysis For Types Of Market Risk, Reasonably Possible Change In Risk Variable, Percent

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Sensitivity Analysis For Types Of Market Risk, Reasonably Possible Decrease In Risk Variable, Impact On Pre-Tax Earnings

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- Definition

The spot exchange rate at the end of the reporting period. Exchange rate is the ratio of exchange for two currencies. Spot exchange rate is the exchange rate for immediate delivery.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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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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The amount of risk exposure associated with financial instruments with a shared characteristic that identifies a concentration of risks. [Refer: Financial instruments, class [member]]

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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