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Impairment charges - Additional information (Detail)
 6 Months Ended 12 Months Ended
Jul. 16, 2019
USD ($)
Jun. 30, 2019
USD ($)
Dec. 31, 2019
USD ($)
$ / Ore
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Disclosure of impairment loss and reversal of impairment loss [line items]          
Impairment charge, net amount     $ 1,658,000,000 $ 104,000,000 $ 481,000,000
Impairment loss recognised in profit or loss     3,487,000,000 132,000,000 796,000,000
Deferred tax assets     3,102,000,000 3,137,000,000 3,137,000,000
Property, plant and equipment [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Impairment loss recognised in profit or loss     3,486,000,000 130,000,000 435,000,000
Australia [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Deferred tax assets     698,000,000 796,000,000  
Canada [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Deferred tax assets     492,000,000 545,000,000  
Mongolia [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Deferred tax assets     704,000,000 703,000,000  
Mongolia [Member] | Copper & Diamonds [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Pre-tax impairment charge net of reversals         0
Assets and liabilities classified as held for sale [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Deferred tax assets       66,000,000  
Oyu Tolgoi Llc [Member] | Copper & Diamonds [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Property development and project management expense $ 5,300,000,000        
Recoverable amount of asset or cash generating unit, percent   20.00%      
Discount rate applied to cash flow projections   8.30%      
Recoverable amount of asset or cash-generating unit   $ 8,300,000,000      
Deferred tax expense (income) relating to origination and reversal of temporary differences   320,000,000      
Deductible temporary differences for which no deferred tax asset is recognised   $ 359,000,000      
Impairment, attributable to noncontrolling interests, percent   66.00%      
Impairment, attributable to parent, percent   34.00%      
Impairment charge, net amount     773,000,000    
Recoverable amount of asset or cash generating unit, assumption   $ 1,500,000,000      
10% Decrease in recoverability   2,200,000,000      
10% Increase in recoverability   2,100,000,000      
Impairment loss recognised in profit or loss     $ 2,240,000,000 0 0
Oyu Tolgoi Llc [Member] | Copper & Diamonds [Member] | Pre Tax [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Pre-tax impairment charge net of reversals   (2,200,000,000)      
Oyu Tolgoi Llc [Member] | Copper & Diamonds [Member] | Post Tax [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Pre-tax impairment charge net of reversals   $ (2,300,000,000)      
Yarwun Alumina Refinery [Member] | Aluminium [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Discount rate applied to cash flow projections     6.60%    
5% Decrease in recoverability, per unit (in tonne) | $ / Ore     17    
5% Decrease in recoverability     $ 505,000,000    
1% increase in post-tax real-terms discount rate, amount     160,000,000    
Recoverable amount of asset or cash-generating unit     911,000,000    
Impairment charge, net amount     799,000,000    
Impairment loss recognised in profit or loss     $ 1,138,000,000 0 0
Impairment loss, annual reduction, percent     30.00%    
ISAL Smelter [Member] | Aluminium [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Discount rate applied to cash flow projections   6.90%      
Recoverable amount of asset or cash-generating unit   $ 302,000,000      
Pre-tax impairment charge net of reversals   (109,000,000)   123,000,000  
Impairment charge, net amount     $ 86,000,000    
Impairment loss recognised in profit or loss     109,000,000 123,000,000 0
ISAL Smelter [Member] | Alufluor Ab [Member] | Aluminium [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Recoverable amount of asset or cash-generating unit   $ 46,000,000      
ISAL Smelter [Member] | Assets and liabilities classified as held for sale [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Business acquisition binding offer amount       $ 345,000,000  
ISAL Smelter [Member] | Assets and liabilities classified as held for sale [Member] | Aluminerie Alouette Inc [Member] | Netherlands [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Percentage of ownership interest to be sold       53.30%  
ISAL Smelter [Member] | Assets and liabilities classified as held for sale [Member] | Alufluor Ab [Member] | Sweden [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Percentage of ownership interest to be sold       50.00%  
Rossing [member] | Energy & Minerals [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Impairment charge, net amount     0    
Impairment loss recognised in profit or loss     0 $ 9,000,000 267,000,000
Rossing [member] | Namibia [Member] | Energy & Minerals [Member] | Property, plant and equipment [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Pre-tax impairment charge         267,000,000
Rossing [member] | Namibia, Dollars | Energy & Minerals [Member] | Property, plant and equipment [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Pre-tax impairment charge       9,000,000  
Argyle Diamond Mine [member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Impairment loss recognised in profit or loss       0  
Argyle Diamond Mine [member] | Copper & Diamonds [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Impairment charge, net amount     0    
Impairment loss recognised in profit or loss     0   172,000,000
Argyle Diamond Mine [member] | Australia [Member] | Copper & Diamonds [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Pre-tax impairment charge         172,000,000
Deferred tax assets         34,000,000
Roughrider [member] | Energy & Minerals [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Impairment charge, net amount     0    
Impairment loss recognised in profit or loss     $ 0 $ 0 357,000,000
Roughrider [member] | Canada [Member] | Energy & Minerals [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Pre-tax impairment charge net of reversals         $ (357,000,000)
Bottom of range [member] | Oyu Tolgoi Llc [Member] | Copper & Diamonds [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Property development and project management expense, estimated increase 1,200,000,000        
Top of range [member] | Oyu Tolgoi Llc [Member] | Copper & Diamonds [Member]          
Disclosure of impairment loss and reversal of impairment loss [line items]          
Property development and project management expense, estimated increase $ 1,900,000,000