XML 199 R192.htm IDEA: XBRL DOCUMENT v3.8.0.1
Financial instruments and risk management - Capital and liquidity risk management - Additional information (Detail)
$ in Millions
 1 Months Ended 12 Months Ended
Nov. 30, 2015
USD ($)
CreditFacility
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Disclosure Of Financial Instruments [Line Items]        
Net debt   $ 3,845 $ 9,587 $ 13,783
Borrowings   15,176 17,630  
Level 1 [member]        
Disclosure Of Financial Instruments [Line Items]        
Borrowings   9,600 11,900  
Borrowings at fair value   10,900 12,900  
Level 3 [member]        
Disclosure Of Financial Instruments [Line Items]        
Borrowings   4,100 4,100  
Borrowings at fair value   $ 4,700 4,600  
Percentage of change in London metal exchange   10.00%    
Period of London metal exchange curve   Ten year    
Decrease in carrying value of forward contract due to long-term metal pricing assumptions   $ 41 38  
Increase in carrying value of forward contract due to long-term metal pricing assumptions   22 64  
Oyu Tolgoi LLC [member]        
Disclosure Of Financial Instruments [Line Items]        
Borrowings   4,300 4,300  
Additional Borrowings   9    
Oyu Tolgoi LLC [member] | MIGA Insured Loan due 2027 [Member]        
Disclosure Of Financial Instruments [Line Items]        
Borrowings   $ 700    
Pre-completion interest rate   2.65%    
Post completion interest rate   3.65%    
Borrowings, maturity   2027    
Oyu Tolgoi LLC [member] | Commercial Banks “B Loan” due 2027 [Member]        
Disclosure Of Financial Instruments [Line Items]        
Borrowings   $ 1,600    
Pre-completion interest rate   3.40%    
Post completion interest rate   4.40%    
Borrowings, maturity   2027    
Oyu Tolgoi LLC [member] | Export Credit Agencies Loan due 2028 [Member]        
Disclosure Of Financial Instruments [Line Items]        
Borrowings   $ 300    
Borrowings, maturity   2028    
Borrowings, interest rate   2.30%    
Oyu Tolgoi LLC [member] | Export Credit Agencies Loan due 2029 [Member]        
Disclosure Of Financial Instruments [Line Items]        
Borrowings   $ 900    
Pre-completion interest rate   3.65%    
Post completion interest rate   4.65%    
Borrowings, maturity   2029    
Oyu Tolgoi LLC [member] | International Financial Institutions “A Loan” due 2030 [Member]        
Disclosure Of Financial Instruments [Line Items]        
Borrowings   $ 900    
Pre-completion interest rate   3.78%    
Post completion interest rate   4.78%    
Borrowings, maturity   2030    
Capital and liquidity risk management [member]        
Disclosure Of Financial Instruments [Line Items]        
Net debt   $ 3,845 $ 9,587  
Net debt to total capital percentage   7.00% 17.00%  
Description of interest coverage on debt   14 times seven times  
Description of rating agencies used   Standard and Poor’s and Moody’s investor services    
Capital and liquidity risk management [member] | Rio Tinto Finance Plc and Rio Tinto Finance Limited [member]        
Disclosure Of Financial Instruments [Line Items]        
Borrowings, maturity A US$1.9 billion facility currently matures in November 2020 and a US$5.6 billion facility (including a US$ denominated same day access swing-line facility) matures in November 2022.      
Multi-currency revolving credit facilities $ 7,500      
Number of extension options in multi-currency revolving credit facilities | CreditFacility 2      
Multi-currency revolving credit facilities period one-year      
Capital and liquidity risk management [member] | Rio Tinto Finance Plc and Rio Tinto Finance Limited [member] | November 2019 [member]        
Disclosure Of Financial Instruments [Line Items]        
Multi-currency revolving credit facilities $ 1,900      
Capital and liquidity risk management [member] | Rio Tinto Finance Plc and Rio Tinto Finance Limited [member] | November 2021 [member]        
Disclosure Of Financial Instruments [Line Items]        
Multi-currency revolving credit facilities $ 5,600      
Capital and liquidity risk management [member] | Rio Tinto Finance (USA) plc and Rio Tinto Finance (USA) Limited [member]        
Disclosure Of Financial Instruments [Line Items]        
Redemption of bonds   $ 2,500 $ 7,500  
Aggregate cash outflow before fees   $ 2,700 7,900  
Bottom of range [Member] | Capital and liquidity risk management [member]        
Disclosure Of Financial Instruments [Line Items]        
Percentage of underlying earnings   40.00%    
Top of range [Member]        
Disclosure Of Financial Instruments [Line Items]        
Maximum carrying value of borrowings repayable, after impact of swaps   $ 1,700 $ 1,700  
Top of range [Member] | Capital and liquidity risk management [member]        
Disclosure Of Financial Instruments [Line Items]        
Percentage of underlying earnings   60.00%