XML 212 R141.htm IDEA: XBRL DOCUMENT v3.19.2
Financial Risk Management - Additional Information (Detail)
t in Thousands
12 Months Ended
Sep. 30, 2019
USD ($)
Jun. 30, 2019
USD ($)
t
Jun. 30, 2018
USD ($)
t
Jun. 30, 2019
AUD ($)
t
Jun. 30, 2019
CLP ($)
t
Jun. 30, 2019
EUR (€)
t
Jun. 30, 2019
GBP (£)
t
Jun. 30, 2018
AUD ($)
t
Jun. 30, 2018
CLP ($)
t
Jun. 30, 2018
EUR (€)
t
Jun. 30, 2018
GBP (£)
t
Disclosure of nature and extent of risks arising from financial instruments [line items]                      
Cash Flow at Risk period of worst expected loss relative to projected business plan cash flows   1 year                  
Principal measurement of risk, confidence level   90.00%                  
Percentage of borrowings exposed to floating interest rate   87.00% 89.00%                
Borrowings   $ 24,113,000,000 $ 26,003,000,000                
TransferBetweenFairValueHierarchyCategories $ 0                    
Weighted average interest rate payable   USD LIBOR + 2.3%                  
Fixed interest rate not swapped to floating rate [member]                      
Disclosure of nature and extent of risks arising from financial instruments [line items]                      
Borrowings   $ 3,019,000,000 3,019,000,000                
Fixed interest rate not swapped to floating rate [member] | At fair value [member]                      
Disclosure of nature and extent of risks arising from financial instruments [line items]                      
Borrowings   $ 3,757,000,000 $ 3,434,000,000                
Interest rate risk [member]                      
Disclosure of nature and extent of risks arising from financial instruments [line items]                      
Reasonable possible change in risk, percentage   1.00% 1.00% 1.00% 1.00% 1.00% 1.00% 1.00% 1.00% 1.00% 1.00%
Effect on equity and profit after taxation, due to reasonable possible change in risk   $ (39,000,000) $ (54,000,000)                
Currency risk [member]                      
Disclosure of nature and extent of risks arising from financial instruments [line items]                      
Effect on equity and profit after taxation, due to reasonable possible change in risk   $ (12,000,000) $ (10,000,000)                
Percentage of net financial liabilities denominated in currency   82.00% 88.00%                
Reasonable possible change in risk, amount       $ 0.01 $ 10 € 0.01 £ 0.01 $ 0.01 $ 10 € 0.01 £ 0.01
Commodity price risk [member]                      
Disclosure of nature and extent of risks arising from financial instruments [line items]                      
Reasonable possible change in risk, percentage   10.00% 10.00% 10.00% 10.00% 10.00% 10.00% 10.00% 10.00% 10.00% 10.00%
Effect on equity and profit after taxation, due to reasonable possible change in risk   $ 55,000,000 $ 9,000,000                
Commodity price risk [member] | Forward commodity and other derivative contracts [member]                      
Disclosure of nature and extent of risks arising from financial instruments [line items]                      
Net asset fair value   199,000,000 210,000,000                
Commodity price risk [member] | Significant financial instruments [member]                      
Disclosure of nature and extent of risks arising from financial instruments [line items]                      
Net asset fair value   $ 202,000,000 $ 216,000,000                
Commodity price risk [member] | Provisionally priced contract [member]                      
Disclosure of nature and extent of risks arising from financial instruments [line items]                      
Reasonable possible change in risk, percentage   10.00% 10.00% 10.00% 10.00% 10.00% 10.00% 10.00% 10.00% 10.00% 10.00%
Effect on equity and profit after taxation, due to reasonable possible change in risk   $ 114,000,000 $ 178,000,000                
Tonnes of copper exposure | t   277 356 277 277 277 277 356 356 356 356