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Financial instruments and risk management (Tables) | 12 Months Ended
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Dec. 31, 2018
Disclosure Of Financial Instruments [Line Items] |
Summary of financial assets by categories | A (a) Financial assets and liabilities by categories
|  |  | IFRS 9 |
|  |  |  |  |  |  |  |  | Fair value |  | Fair value |
|  |  |  |  |  |  |  |  | through other |  | through |
|  |  |  |  |  | Amortised |  | comprehensive |  | profit and |
|  |  | Total |  | cost |  | income |  | loss |
At 31 December 2018 |  | Note | US$m |  | US$m |  | US$m |  | US$m |
Financial assets |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents |  | 21 |  | 10,773 |  |  | 2,779 |  |  | - |  |  | 7,994 |
Trade and other financial receivables (a) (b) |  | 18 |  | 3,007 |  |  | 2,015 |  |  | - |  |  | 992 |
Equity shares and quoted funds |  | 20 |  | 130 |  |  | - |  |  | 53 |  |  | 77 |
Other investments, including loans (c) |  | 20 |  | 2,782 |  |  | 6 |  |  | - |  |  | 2,776 |
Derivatives related to net debt: designated as hedges (d) |  | 20, 24 |  | 70 |  |  | - |  |  | - |  |  | 70 |
Derivatives and embedded derivatives not related to net debt: not designated as hedges (d) |  | 20 |  | 432 |  |  | - |  |  | - |  |  | 432 |
Embedded derivatives not related to net debt: designated as hedges (d) |  | 20 |  | 54 |  |  | - |  |  | - |  |  | 54 |
Loans to equity accounted units including quasi equity loans |  |  |  | 167 |  |  | 167 |  |  | - |  |  | - |
Total financial assets |  |  |  | 17,415 |  |  | 4,967 |  |  | 53 |  |  | 12,395 |
Financial liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |
Trade and other financial payables (e) |  | 25 |  | (5,552 | ) |  | (5,513 | ) |  |  |  |  | (39 | )
Short-term borrowings and bank overdrafts |  | 22 |  | (312 | ) |  | (312 | ) |  |  |  |  | - |
Medium-term and long-term borrowings |  | 22 |  | (12,440 | ) |  | (12,440 | ) |  |  |  |  | - |
Derivatives related to net debt: designated as hedges (d) |  | 22, 24 |  | (358 | ) |  | - |  |  |  |  |  | (358 | )
Derivatives and embedded derivatives not related to net debt: not designated as hedges (d) |  | 22 |  | (98 | ) |  | - |  |  |  |  |  | (98 | )
Embedded derivatives not related to net debt: designated as hedges (d) |  | 22 |  | (46 | ) |  | - |  |  |  |  |  | (46 | )
Other financial liabilities |  | 22 |  | (666 | ) |  | (666 | ) |  |  |  |  | - |
Total financial liabilities |  |  |  | (19,472 | ) |  | (18,931 | ) |  |  |  |  | (541 | )
|  |  |  |  |  | IAS 39 |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  | Held to maturity |
|  |  |  |  |  |  |  |  | Available |  |  |  |  | assets/other |
|  |  |  |  |  | Loans and |  | for sale |  | Held at |  | financial |
|  |  | Total |  | receivables |  | securities |  | fair value |  | liabilities |
At 31 December 2017 |  | Note | US$m |  | US$m |  | US$m |  | US$m |  | US$m |
Financial assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents |  | 21 |  | 10,550 |  |  | 10,550 |  |  | - |  |  | - |  |  | - |
Trade and other financial receivables (a) (b) |  | 18 |  | 2,985 |  |  | 2,895 |  |  | - |  |  | 90 |  |  | - |
Equity shares and quoted funds |  | 20 |  | 136 |  |  | - |  |  | 136 |  |  | - |  |  | - |
Other investments, including loans (c) |  | 20 |  | 1,152 |  |  | 15 |  |  | - |  |  | 1,125 |  |  | 12 |
Derivatives related to net debt: designated as hedges (d) |  | 20, 24 |  | 99 |  |  | - |  |  | - |  |  | 99 |  |  | - |
Derivatives and embedded derivatives not related to net debt: not designated as hedges (d) |  | 20 |  | 168 |  |  | - |  |  | - |  |  | 168 |  |  | - |
Loans to equity accounted units including quasi equity loans |  |  |  | 198 |  |  | 198 |  |  | - |  |  | - |  |  | - |
Total financial assets |  |  |  | 15,288 |  |  | 13,658 |  |  | 136 |  |  | 1,482 |  |  | 12 |
Financial liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Trade and other financial payables (e) |  | 25 |  | (5,922 | ) |  |  |  |  |  |  |  | (15 | ) |  | (5,907 | )
Short-term borrowings and bank overdrafts |  | 22 |  | (552 | ) |  |  |  |  |  |  |  | - |  |  | (552 | )
Medium-term and long-term borrowings |  | 22 |  | (14,624 | ) |  |  |  |  |  |  |  | - |  |  | (14,624 | )
Derivatives related to net debt: designated as hedges (d) |  | 22, 24 |  | (276 | ) |  |  |  |  |  |  |  | (276 | ) |  | - |
Other derivatives and embedded derivatives: not designated as hedges (d) |  | 22 |  | (255 | ) |  |  |  |  |  |  |  | (255 | ) |  | - |
Other financial liabilities |  | 22 |  | (345 | ) |  |  |  |  |  |  |  | - |  |  | (345 | )
Total financial liabilities |  |  |  | (21,974 | ) |  |  |  |  |  |  |  | (546 | ) |  | (21,428 | )
(a) | Trade and other financial receivables comprise of trade receivables, other financial receivables, and amounts due from equity accounted units within note 18.
(b) | Under IFRS 9, provisionally priced receivables are fair valued. In the prior year, under IAS 39, only the embedded pricing derivatives, which were separated from the host receivables, were fair valued.
(c) | Other investments, including loans, comprise US$2,522 million (2017: US$958 million) of highly liquid financial assets in managed investment funds classified as held for trading.
(d) | These financial assets and liabilities in aggregate agree to total derivative financial instruments disclosed in notes 20 and 22.
(e) | Trade and other financial payables comprise trade payables, other financial payables, accruals and amounts due to equity accounted units within note 25. The trade and other payables held at fair value are valued using level 2 inputs.
Summary of financial liabilities by categories | A (a) Financial assets and liabilities by categories
|  |  | IFRS 9 |
|  |  |  |  |  |  |  |  | Fair value |  | Fair value |
|  |  |  |  |  |  |  |  | through other |  | through |
|  |  |  |  |  | Amortised |  | comprehensive |  | profit and |
|  |  | Total |  | cost |  | income |  | loss |
At 31 December 2018 |  | Note | US$m |  | US$m |  | US$m |  | US$m |
Financial assets |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents |  | 21 |  | 10,773 |  |  | 2,779 |  |  | - |  |  | 7,994 |
Trade and other financial receivables (a) (b) |  | 18 |  | 3,007 |  |  | 2,015 |  |  | - |  |  | 992 |
Equity shares and quoted funds |  | 20 |  | 130 |  |  | - |  |  | 53 |  |  | 77 |
Other investments, including loans (c) |  | 20 |  | 2,782 |  |  | 6 |  |  | - |  |  | 2,776 |
Derivatives related to net debt: designated as hedges (d) |  | 20, 24 |  | 70 |  |  | - |  |  | - |  |  | 70 |
Derivatives and embedded derivatives not related to net debt: not designated as hedges (d) |  | 20 |  | 432 |  |  | - |  |  | - |  |  | 432 |
Embedded derivatives not related to net debt: designated as hedges (d) |  | 20 |  | 54 |  |  | - |  |  | - |  |  | 54 |
Loans to equity accounted units including quasi equity loans |  |  |  | 167 |  |  | 167 |  |  | - |  |  | - |
Total financial assets |  |  |  | 17,415 |  |  | 4,967 |  |  | 53 |  |  | 12,395 |
Financial liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |
Trade and other financial payables (e) |  | 25 |  | (5,552 | ) |  | (5,513 | ) |  |  |  |  | (39 | )
Short-term borrowings and bank overdrafts |  | 22 |  | (312 | ) |  | (312 | ) |  |  |  |  | - |
Medium-term and long-term borrowings |  | 22 |  | (12,440 | ) |  | (12,440 | ) |  |  |  |  | - |
Derivatives related to net debt: designated as hedges (d) |  | 22, 24 |  | (358 | ) |  | - |  |  |  |  |  | (358 | )
Derivatives and embedded derivatives not related to net debt: not designated as hedges (d) |  | 22 |  | (98 | ) |  | - |  |  |  |  |  | (98 | )
Embedded derivatives not related to net debt: designated as hedges (d) |  | 22 |  | (46 | ) |  | - |  |  |  |  |  | (46 | )
Other financial liabilities |  | 22 |  | (666 | ) |  | (666 | ) |  |  |  |  | - |
Total financial liabilities |  |  |  | (19,472 | ) |  | (18,931 | ) |  |  |  |  | (541 | )
|  |  |  |  |  | IAS 39 |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  | Held to maturity |
|  |  |  |  |  |  |  |  | Available |  |  |  |  | assets/other |
|  |  |  |  |  | Loans and |  | for sale |  | Held at |  | financial |
|  |  | Total |  | receivables |  | securities |  | fair value |  | liabilities |
At 31 December 2017 |  | Note | US$m |  | US$m |  | US$m |  | US$m |  | US$m |
Financial assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents |  | 21 |  | 10,550 |  |  | 10,550 |  |  | - |  |  | - |  |  | - |
Trade and other financial receivables (a) (b) |  | 18 |  | 2,985 |  |  | 2,895 |  |  | - |  |  | 90 |  |  | - |
Equity shares and quoted funds |  | 20 |  | 136 |  |  | - |  |  | 136 |  |  | - |  |  | - |
Other investments, including loans (c) |  | 20 |  | 1,152 |  |  | 15 |  |  | - |  |  | 1,125 |  |  | 12 |
Derivatives related to net debt: designated as hedges (d) |  | 20, 24 |  | 99 |  |  | - |  |  | - |  |  | 99 |  |  | - |
Derivatives and embedded derivatives not related to net debt: not designated as hedges (d) |  | 20 |  | 168 |  |  | - |  |  | - |  |  | 168 |  |  | - |
Loans to equity accounted units including quasi equity loans |  |  |  | 198 |  |  | 198 |  |  | - |  |  | - |  |  | - |
Total financial assets |  |  |  | 15,288 |  |  | 13,658 |  |  | 136 |  |  | 1,482 |  |  | 12 |
Financial liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Trade and other financial payables (e) |  | 25 |  | (5,922 | ) |  |  |  |  |  |  |  | (15 | ) |  | (5,907 | )
Short-term borrowings and bank overdrafts |  | 22 |  | (552 | ) |  |  |  |  |  |  |  | - |  |  | (552 | )
Medium-term and long-term borrowings |  | 22 |  | (14,624 | ) |  |  |  |  |  |  |  | - |  |  | (14,624 | )
Derivatives related to net debt: designated as hedges (d) |  | 22, 24 |  | (276 | ) |  |  |  |  |  |  |  | (276 | ) |  | - |
Other derivatives and embedded derivatives: not designated as hedges (d) |  | 22 |  | (255 | ) |  |  |  |  |  |  |  | (255 | ) |  | - |
Other financial liabilities |  | 22 |  | (345 | ) |  |  |  |  |  |  |  | - |  |  | (345 | )
Total financial liabilities |  |  |  | (21,974 | ) |  |  |  |  |  |  |  | (546 | ) |  | (21,428 | )
(a) | Trade and other financial receivables comprise of trade receivables, other financial receivables, and amounts due from equity accounted units within note 18.
(b) | Under IFRS 9, provisionally priced receivables are fair valued. In the prior year, under IAS 39, only the embedded pricing derivatives, which were separated from the host receivables, were fair valued.
(c) | Other investments, including loans, comprise US$2,522 million (2017: US$958 million) of highly liquid financial assets in managed investment funds classified as held for trading.
(d) | These financial assets and liabilities in aggregate agree to total derivative financial instruments disclosed in notes 20 and 22.
(e) | Trade and other financial payables comprise trade payables, other financial payables, accruals and amounts due to equity accounted units within note 25. The trade and other payables held at fair value are valued using level 2 inputs.
Summary of credit ratings | The table below summarises the credit ratings attributed to the Group by Standard & Poor’s and Moody’s investor services as at 31 December.
|  |  |  |  |  | 2018 |  |  | 2017 |
Long-term rating(a) |  |  |  |  | A/A3 |  | A-/A3 |
Short-term rating(a) |  |  |  |  | A-1/P-2 |  | A-1/P-2 |
Outlook |  |  |  |  | Stable/Stable |  | Positive/Stable |
Maturity analysis for non-derivative financial liabilities and derivative financial liabilities | The table below summarises the maturity profile of the Group’s financial liabilities based on contractual undiscounted payments. It will therefore not necessarily agree with the amounts disclosed in the balance sheet. Financial liability analysis At 31 December 2018
| Within 1 |  | Between |  | Between |  | Between |  | Between |  |  |  |  |  |  |
| year or on |  | 1 and 2 |  | 2 and 3 |  | 3 and 4 |  | 4 and 5 |  | After |  |  |  |
| demand |  | years |  | years |  | years |  | years |  | 5 years |  | Total |
(Outflows)/inflows | US$m |  | US$m |  | US$m |  | US$m |  | US$m |  | US$m |  | US$m |
Non-derivative financial liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Trade and other financial payables |  | (5,129 | ) |  | (423 | ) |  | - |  |  | - |  |  | - |  |  | - |  |  | (5,552 | )
Borrowings before swaps |  | (312 | ) |  | (562 | ) |  | (166 | ) |  | (660 | ) |  | (741 | ) |  | (10,476 | ) |  | (12,917 | )
Expected future interest payments (a) |  | (651 | ) |  | (653 | ) |  | (636 | ) |  | (630 | ) |  | (586 | ) |  | (4,082 | ) |  | (7,238 | )
Other financial liabilities |  | (666 | ) |  | - |  |  | - |  |  | - |  |  | - |  |  | - |  |  | (666 | )
Derivative financial liabilities (b) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives related to net debt - net settled |  | (36 | ) |  | (36 | ) |  | (36 | ) |  | (36 | ) |  | 4 |  |  | (8 | ) |  | (148 | )
Derivatives related to net debt - gross settled (a): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
– gross inflows |  | 48 |  |  | 508 |  |  | 39 |  |  | 39 |  |  | 39 |  |  | 1,278 |  |  | 1,951 |
– gross outflows |  | (79 | ) |  | (595 | ) |  | (58 | ) |  | (58 | ) |  | (58 | ) |  | (1,581 | ) |  | (2,429 | )
Derivatives not related to net debt - net settled |  | (27 | ) |  | (13 | ) |  | (5 | ) |  | (5 | ) |  | (5 | ) |  | (28 | ) |  | (83 | )
Derivatives not related to net debt - gross settled: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
– gross inflows |  | 1,664 |  |  | - |  |  | - |  |  | - |  |  | - |  |  | - |  |  | 1,664 |
– gross outflows |  | (1,733 | ) |  | - |  |  | - |  |  | - |  |  | - |  |  | - |  |  | (1,733 | )
Total |  | (6,921 | ) |  | (1,774 | ) |  | (862 | ) |  | (1,350 | ) |  | (1,347 | ) |  | (14,897 | ) |  | (27,151 | )
At 31 December 2017
| Within 1 |  | Between |  | Between |  | Between |  | Between |  |  |  |  |  |  |
| year or on |  | 1 and 2 |  | 2 and 3 |  | 3 and 4 |  | 4 and 5 |  | After |  |  |  |
| demand |  | years |  | years |  | years |  | years |  | 5 years |  | Total |
(Outflows)/inflows | US$m |  | US$m |  | US$m |  | US$m |  | US$m |  | US$m |  | US$m |
Non-derivative financial liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Trade and other financial payables |  | (5,488 | ) |  | (434 | ) |  | - |  |  | - |  |  | - |  |  | - |  |  | (5,922 | )
Borrowings before swaps |  | (552 | ) |  | (148 | ) |  | (1,011 | ) |  | (916 | ) |  | (1,283 | ) |  | (11,387 | ) |  | (15,297 | )
Expected future interest payments (a) |  | (679 | ) |  | (673 | ) |  | (670 | ) |  | (638 | ) |  | (606 | ) |  | (4,553 | ) |  | (7,819 | )
Other financial liabilities |  | (302 | ) |  | (43 | ) |  | - |  |  | - |  |  | - |  |  | - |  |  | (345 | )
Derivative financial liabilities (b) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives related to net debt - net settled |  | 10 |  |  | 10 |  |  | 14 |  |  | 11 |  |  | 7 |  |  | 36 |  |  | 88 |
Derivatives related to net debt - gross settled (a): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
– gross inflows |  | 62 |  |  | 62 |  |  | 958 |  |  | 44 |  |  | 44 |  |  | 1,493 |  |  | 2,663 |
– gross outflows |  | (82 | ) |  | (82 | ) |  | (1,051 | ) |  | (55 | ) |  | (55 | ) |  | (1,741 | ) |  | (3,066 | )
Derivatives not related to net debt - net settled |  | (43 | ) |  | (36 | ) |  | (33 | ) |  | (24 | ) |  | (21 | ) |  | (138 | ) |  | (295 | )
Derivatives not related to net debt - gross settled: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
– gross inflows |  | 795 |  |  | - |  |  | - |  |  | - |  |  | - |  |  | - |  |  | 795 |
– gross outflows |  | (802 | ) |  | - |  |  | - |  |  | - |  |  | - |  |  | - |  |  | (802 | )
Total |  | (7,081 | ) |  | (1,344 | ) |  | (1,793 | ) |  | (1,578 | ) |  | (1,914 | ) |  | (16,290 | ) |  | (30,000 | )
(a) | Interest payments have been projected using interest rates applicable at the end of the applicable financial year. Where debt is subject to variable interest rates, future interest payments are subject to change in line with market rates.
(b) | The maturity grouping is based on the earliest payment date.
Summary of impact of hedging instrument on statement of financial position | The impact of the hedging instrument on the Group balance sheet is as follows:
At 31 December 2018 | Notional amount US$m | Carrying value US$m | Line item in the statement of financial position | Change in fair value used for measuring ineffectiveness for the period US$m
Aluminium embedded derivatives separated from the power contract (a) | 1,786 | 8 | Other financial asset (US$54m) and other financial liability (US$46m) | 205
(a) | Aluminium embedded derivatives (forward contracts and options) are contained within certain aluminium smelter electricity purchase contracts.
The impact of the hedged item on the Group balance sheet is:
At 31 December 2018 | Change in fair value used for measuring ineffectiveness for the period US$m | Cash flow hedge reserve US$m
Highly probable forecast aluminium sales | (182) | 179
The effect of the cash flow hedge in the statement of profit or loss and other comprehensive income (OCI) is:
At 31 December 2018 | Total hedging gain recognised in OCI US$m | Ineffectiveness recognised in profit or loss US$m | Line item in the statement of profit or loss | Amount reclassified from OCI to profit or loss US$m | Line item in the statement of profit or loss
Highly probable forecast aluminium sales | 181 | 24 | Net operating costs (raw materials, consumables, repairs and maintenance) | 2 | Consolidated sales revenue
Summary of market price relevant to the aluminum purchase price swaps outstanding |
| Change in market prices | 2018 US$m | 2017 US$m
Effect on net earnings | +10% | (102) | (203)
-10% | 35 | 212
Effect on equity | +10% | (101) | -
-10% | 103 | -
Summary of maximum credit risk exposure of the Group's financial assets |
|  |  |  |  |  | 2018 |  |  | 2017 |
|  |  |  | Note | US$m |  | US$m |
Cash and cash equivalents |  |  |  | 21 |  | 10,773 |  |  | 10,550 |
Trade and other financial receivables |  |  |  | 18 |  | 3,007 |  |  | 2,985 |
Investments |  |  |  | 20 |  | 2,782 |  |  | 1,152 |
Derivative assets |  |  |  | 20 |  | 556 |  |  | 267 |
Loans to equity accounted units |  |  |  |  |  | 38 |  |  | 39 |
Total |  |  |  |  |  | 17,156 |  |  | 14,993 |
Summary by currency, the Group's net debt, after taking into account relevant cross currency interest rate swaps and foreign exchange contracts | The table below summarises, by currency, the Group’s net debt, after taking into account relevant cross-currency interest rate swaps and foreign exchange contracts:
|  | Total |  | Derivatives |  | Cash and |  |  |  |  | Net cash/ |  | Net cash/ |
|  | borrowings |  | related to net |  | cash |  | Other |  | (debt) |  | (debt) |
|  | excluding overdrafts |  | debt |  | equivalents |  | investments |  |  | 2018 |  |  | 2017 |
Net cash/(debt) by currency |  | US$m |  | US$m |  | US$m |  | US$m |  | US$m |  | US$m |
US dollar |  |  | (12,080 | ) |  | (288 | ) |  | 10,310 |  |  | 2,522 |  |  | 464 |  |  | (3,628 | )
Australian dollar |  |  | (472 | ) |  | - |  |  | 217 |  |  | - |  |  | (255 | ) |  | (208 | )
Euro |  |  | (39 | ) |  | - |  |  | 17 |  |  | - |  |  | (22 | ) |  | (58 | )
South African rand |  |  | - |  |  | - |  |  | 95 |  |  | - |  |  | 95 |  |  | 59 |
Canadian dollar |  |  | (157 | ) |  | - |  |  | 23 |  |  | - |  |  | (134 | ) |  | (148 | )
Other |  |  | (3 | ) |  | - |  |  | 110 |  |  | - |  |  | 107 |  |  | 138 |
Total |  |  | (12,751 | ) |  | (288 | ) |  | 10,772 |  |  | 2,522 |  |  | 255 |  |  | (3,845 | )
|  | Total |  | Derivatives |  | Cash and |  |  |  |  | Net cash/ |  | Net cash/ |
|  | borrowings |  | related to net |  | cash |  | Other |  | (debt) |  | (debt) |
|  | excluding overdrafts |  | debt |  | equivalents |  | investments |  |  | 2018 |  |  | 2017 |
Net cash/(debt) by currency |  | US$m |  | US$m |  | US$m |  | US$m |  | US$m |  | US$m |
US dollar |  |  | (12,080 | ) |  | (288 | ) |  | 10,310 |  |  | 2,522 |  |  | 464 |  |  | (3,628 | )
Australian dollar |  |  | (472 | ) |  | - |  |  | 217 |  |  | - |  |  | (255 | ) |  | (208 | )
Euro |  |  | (39 | ) |  | - |  |  | 17 |  |  | - |  |  | (22 | ) |  | (58 | )
South African rand |  |  | - |  |  | - |  |  | 95 |  |  | - |  |  | 95 |  |  | 59 |
Canadian dollar |  |  | (157 | ) |  | - |  |  | 23 |  |  | - |  |  | (134 | ) |  | (148 | )
Other |  |  | (3 | ) |  | - |  |  | 110 |  |  | - |  |  | 107 |  |  | 138 |
Total |  |  | (12,751 | ) |  | (288 | ) |  | 10,772 |  |  | 2,522 |  |  | 255 |  |  | (3,845 | )
Summary of derivative financial instruments |
|  |  |  | Total fair value |
|  |  |  | 2018 |  | 2017 |
|  |  |  | Asset |  | Liability |  | Asset |  | Liability |
|  |  |  | US$m |  | US$m |  | US$m |  | US$m |
Derivatives designated as hedges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate swaps (a) |  |  |  |  | 70 |  |  | (137 | ) |  | 99 |  |  | (127 | )
Cross-currency interest rate swaps (b) |  |  |  |  | - |  |  | (221 | ) |  | - |  |  | (149 | )
Aluminium embedded derivatives (c) |  |  |  |  | 54 |  |  | (46 | ) |  | - |  |  | - |
Total derivatives designated as hedges |  |  |  |  | 124 |  |  | (404 | ) |  | 99 |  |  | (276 | )
Derivatives not designated as hedges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Currency forward contracts, options and swaps |  |  |  |  | - |  |  | (68 | ) |  | 7 |  |  | (2 | )
Aluminium forward contracts (d) |  |  |  |  | 26 |  |  | (19 | ) |  | 21 |  |  | (9 | )
Aluminium embedded derivatives (c) |  |  |  |  | 346 |  |  | - |  |  | 140 |  |  | (238 | )
Other embedded derivatives |  |  |  |  | 6 |  |  | - |  |  | - |  |  | (5 | )
Other commodity contracts |  |  |  |  | 54 |  |  | (11 | ) |  | - |  |  | (1 | )
Total derivatives not designated as hedges |  |  |  |  | 432 |  |  | (98 | ) |  | 168 |  |  | (255 | )
Total derivative instruments |  |  |  |  | 556 |  |  | (502 | ) |  | 267 |  |  | (531 | )
Analysed by maturity: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Less than 1 year |  |  |  |  | 88 |  |  | (95 | ) |  | 29 |  |  | (50 | )
Between 1 and 5 years |  |  |  |  | 153 |  |  | (205 | ) |  | 31 |  |  | (233 | )
More than 5 years |  |  |  |  | 315 |  |  | (202 | ) |  | 207 |  |  | (248 | )
Total |  |  |  |  | 556 |  |  | (502 | ) |  | 267 |  |  | (531 | )
Total net derivative instruments |  |  |  |  | 54 |  |  |  |  |  |  |  |  | (264 | )
|  |  |  |  | 2018 |  |  | 2017 |
Reconciliation to balance sheet |  |  | Note | US$m |  | US$m |
Non-current assets |  |  | 20 |  | 468 |  |  | 238 |
Current assets |  |  | 20 |  | 88 |  |  | 29 |
Current liabilities |  |  | 22 |  | (95 | ) |  | (50 | )
Non-current liabilities |  |  | 22 |  | (407 | ) |  | (481 | )
Total net derivative instruments |  |  |  |  | 54 |  |  | (264 | )
(a) | The interest rate swaps are used to convert certain fixed rate borrowings to a floating rate. For further details, see note 22.
(b) | The cross-currency interest rate swaps are used to convert non-US dollar denominated borrowings to either fixed or floating US dollar borrowings. For further details see note 22.
(d) | Aluminium embedded derivatives (forward contracts and options) are contained within certain aluminium smelter electricity purchase contracts. These contracts reduce the Group’s margin exposure to movements in the aluminium price.
(c) | The aluminium forward contracts are entered into to convert aluminium sales made at a fixed price to the market price (LME cash). In 2017 and 2018 these contracts were not designated as hedges.
Summary of fair value of financial instruments | The carrying amounts and fair values of all of the Group’s financial instruments which are not carried at an amount which approximates their fair value at 31 December 2018 and 31 December 2017 are shown in the following table. The fair values of the Group’s cash equivalents and loans to equity accounted units approximate their carrying values as a result of their short maturity or because they carry floating rates of interest.
|  |  |  | 31 December 2018 |  | 31 December 2017 |
|  |  |  | Carrying |  | Fair |  | Carrying |  | Fair |
|  |  |  | value |  | value |  | value |  | value |
|  |  | Note | US$m |  | US$m |  | US$m |  | US$m |
Short-term borrowings |  |  | 22 |  | (312 | ) |  | (312 | ) |  | (552 | ) |  | (552 | )
Medium-term and long-term borrowings |  |  | 22 |  | (12,440 | ) |  | (13,554 | ) |  | (14,624 | ) |  | (16,385 | )
C (a) Valuation hierarchy The table below shows the financial instruments carried at fair value by valuation method, under IFRS 9, at 31 December 2018.
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Not held |
|  |  |  |  | Total |  | Level 1 (a) |  | Level 2 (b) |  | Level 3 (c) |  | at fair value |
|  | Note |  | US$m |  | US$m |  | US$m |  | US$m |  | US$m |
Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents |  |  |  |  |  | 10,773 |  |  | 7,994 |  |  | - |  |  | - |  |  | 2,779 |
Investments in equity shares and funds |  |  |  |  |  | 130 |  |  | 92 |  |  | - |  |  | 38 |  |  | - |
Other investments, including loans (d) |  | 20 |  |  | 2,782 |  |  | 2,544 |  |  | - |  |  | 232 |  |  | 6 |
Trade and other financial receivables (e) |  |  | 18 |  |  | 3,007 |  |  | 20 |  |  | 972 |  |  | - |  |  | 2,015 |
|  |  |  |  |  | 16,692 |  |  | 10,650 |  |  | 972 |  |  | 270 |  |  | 4,800 |
Derivatives (net) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Forward contracts and option contracts: designated as hedges(f) (Section B) |  |  |  |  |  | 8 |  |  | - |  |  | - |  |  | 8 |  |  | - |
Forward contracts and option contracts, not designated as hedges (f) (Section B) |  |  |  |  | 334 |  |  | - |  |  | (25 | ) |  | 359 |  |  | - |
Derivatives related to net debt (Section B) (g) |  |  |  |  |  | (288 | ) |  | - |  |  | (288 | ) |  | - |  |  | - |
Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Trade and other financial payables |  |  | 25 |  |  | (5,552 | ) |  | - |  |  | (39 | ) |  | - |  |  | (5,513 | )
Total |  |  |  |  |  | 11,194 |  |  | 10,650 |  |  | 620 |  |  | 637 |  |  | (713 | )
The table below shows the financial instruments carried at fair value by valuation method, under IAS 39, at 31 December 2017.
|  |  |  |  |  |  |  |  |  |  |  |  |  |  | Not held |
|  |  | Total |  | Level 1 (a) |  | Level 2 (b) |  | Level 3 (c) |  | at fair value |
|  | Note | US$m |  | US$m |  | US$m |  | US$m |  | US$m |
Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents |  |  |  | 10,550 |  |  | - |  |  | - |  |  | - |  |  | 10,550 |
Equity shares and quoted funds |  | 20 |  | 136 |  |  | 88 |  |  | - |  |  | 3 |  |  | 45 |
Other investments, including loans (d) |  | 20 |  | 1,152 |  |  | 1,037 |  |  | - |  |  | 88 |  |  | 27 |
Trade and other receivables (e) |  |  |  | 2,985 |  |  | - |  |  | 90 |  |  | - |  |  | 2,895 |
|  |  |  | 14,823 |  |  | 1,125 |  |  | 90 |  |  | 91 |  |  | 13,517 |
Derivatives (net) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Forward contracts and option contracts, not designated as hedges (f) (Section B) |  |  |  | (87 | ) |  | - |  |  | 11 |  |  | (98 | ) |  | - |
Derivatives related to net debt (Section B) (g) |  |  |  | (177 | ) |  | - |  |  | (177 | ) |  | - |  |  | - |
Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Trade and other financial payables |  |  |  | (5,922 | ) |  | - |  |  | (15 | ) |  | - |  |  | (5,907 | )
Total |  |  |  | 8,637 |  |  | 1,125 |  |  | (91 | ) |  | (7 | ) |  | 7,610 |
(a) | Valuation is based on unadjusted quoted prices in active markets for identical financial instruments. This category includes listed equity shares and other quoted funds.
(b) | Valuation is based either on inputs which include quoted prices for similar instruments or identical instruments in markets which are not considered to be active, or on inputs, which are directly or indirectly based on observable market data.
(c) | Valuation is based on inputs that are not based on observable market data (unobservable inputs).
(d) | Other investments, including loans, comprise: cash deposits in rehabilitation funds, government bonds, managed investment funds and royalty receivables. The royalty receivables are valued based on future expected output as well as future expected commodity prices.
(e) | Trade receivables include provisionally priced receivables relating to sales contracts where the selling price is determined after delivery to the customer, based on the market price at the relevant quotation point stipulated in the contract. Revenue is recognised on provisionally priced sales based on the forward selling price for the period stipulated in the contract. Under IFRS 9, provisionally priced receivables at 31 December 2018 were US$889 million and were fair valued. In the prior year, under IAS 39, only the embedded pricing derivatives, which were separated from the host receivables, were fair valued (31 December 2017: US$90 million).
(f) | Level 3 derivatives consist of derivatives embedded in electricity purchase contracts linked to the LME with terms expiring between 2025 and 2030 (2017: 2018 and 2030). The embedded derivatives are measured using discounted cash flows and option model valuation techniques. Long-term embedded derivatives with a fair value of US$338 million at 31 December 2018 (2017: US$(98) million) are valued using significant unobservable inputs as the term of the derivative extends beyond the forward curve for aluminium and includes unobservable market premium prices. In valuing these derivatives, aluminium prices are flatlined beyond the market forward curve and increased by projected inflation up to the date of expiry of each contract. Future market premiums are estimated based on historical trends. The range of market prices are US$2,426 per metric tonne in 2029 to US$2,507 in 2030 (2017: US$2,679 per metric tonne in 2028 to US$2,848 in 2030).
(g) | Interest rate and currency interest rate swaps are valued using applicable market-quoted swap yield curves adjusted for relevant basis and credit default spreads. Currency interest rate swap valuations also use market-quoted foreign exchange rates. A discounted cash flow approach is applied to the cash flows derived from the inputs to determine fair value.
Summary of capital and liquidity risk management |
|  |  |  |  |  | 2018 |  |  | 2017 |
Total capital |  |  |  | Note | US$m |  | US$m |
Equity attributable to owners of Rio Tinto (see Group balance sheet) |  |  |  |  |  | 43,686 |  |  | 44,711 |
Equity attributable to non-controlling interests (see Group balance sheet) |  |  |  |  |  | 6,137 |  |  | 6,404 |
Net debt |  |  |  | 24 |  | (255 | ) |  | 3,845 |
Total capital |  |  |  |  |  | 49,568 |  |  | 54,960 |
Summary of effect of the cash flow hedge in statement of profit or loss and other comprehensive income (OCI) | The effect of the cash flow hedge in the statement of profit or loss and other comprehensive income (OCI) is:
At 31 December 2018 | Total hedging gain recognised in OCI US$m | Ineffectiveness recognised in profit or loss US$m | Line item in the statement of profit or loss | Amount reclassified from OCI to profit or loss US$m | Line item in the statement of profit or loss
Highly probable forecast aluminium sales | 181 | 24 | Net operating costs (raw materials, consumables, repairs and maintenance) | 2 | Consolidated sales revenue
Disclosure of effect of changes in foreign exchange rates on earnings | Gains/(losses) associated with 10% strengthening of the US dollar
|  |  |  |  |  |  |  |  |  | Of which |  |  |  |
|  |  |  |  |  |  |  |  |  | amount |  |  |  |
|  |  |  | Closing |  | Effect on |  | impacting |  | Impact |
|  |  |  | exchange |  | net |  | underlying |  | directly |
|  |  |  | rate |  | earnings |  | earnings |  | on equity |
Currency exposure |  |  |  | US cents |  | US$m |  | US$m |  | US$m |
Australian dollar |  |  |  |  | 70 |  |  | 346 |  |  | 1 |  |  | (993 | )
Canadian dollar |  |  |  |  | 73 |  |  | (82 | ) |  | 7 |  | - |
Euro |  |  |  |  | 114 |  |  | 202 |  |  | 5 |  | - |
At 31 December 2017 Gains/(losses) associated with 10% strengthening of the US dollar
|  |  |  |  |  |  |  |  |  | Of which |  |  |  |
|  |  |  |  |  |  |  |  |  | amount |  |  |  |
|  |  |  | Closing |  | Effect on |  | impacting |  | Impact |
|  |  |  | exchange |  | net |  | underlying |  | directly |
|  |  |  | rate |  | earnings |  | earnings |  | on equity |
Currency exposure |  |  |  | US cents |  | US$m |  | US$m |  | US$m |
Australian dollar |  |  |  |  | 78 |  |  | 608 |  |  | 47 |  |  | (1,657 | )
Canadian dollar |  |  |  |  | 79 |  |  | (134 | ) |  | 3 |  | - |
Euro |  |  |  |  | 120 |  |  | 165 |  |  | (2 | ) | - |
Summary of changes in the fair value of Level 3 financial assets and financial liabilities | The table below shows the summary of changes in the fair value of the Group’s level 3 financial assets and financial liabilities.
|  |  |  |  | 2018 |  | 2017 |
|  |  |  | Level 3 financial assets |  | Level 3 financial assets |
|  |  |  | and financial liabilities |  | and financial liabilities |
|  |  |  | US$m |  | US$m |
Opening balance |  |  |  |  | (7 | ) |  | 479 |
Adjustment from transition to IFRS 9 |  |  |  |  | 19 |  |  | - |
Currency translation adjustments |  |  |  |  | (23 | ) |  | 8 |
Total realised gains/(losses) included in: |  |  |  |  |  |  |  |  |
– consolidated sales revenue |  |  |  |  | - |  |  | 1 |
– net operating costs |  |  |  |  | 9 |  |  | (5 | )
Total unrealised gains/(losses) included in: |  |  |  |  |  |  |  |  |
- consolidated sales revenue |  |  |  |  | - |  |  | 17 |
– net operating costs (a) |  |  |  |  | 375 |  |  | (508 | )
Total unrealised gains transferred into other comprehensive income through cash flow hedges |  |  |  |  | 181 |  |  | - |
Additions |  |  |  |  | 67 |  |  | - |
Disposals/maturity of financial instruments |  |  |  |  | (6 | ) |  | (5 | )
Transfers |  |  |  |  | 22 |  |  | 6 |
Closing balance |  |  |  |  | 637 |  |  | (7 | )
Total gains/(losses) for the year included in the income statement for assets and liabilities held at year end |  |  |  |  | 346 |  |  | (491 | )
|  |  |  |  | 2018 |  | 2017 |
|  |  |  | Level 3 financial assets |  | Level 3 financial assets |
|  |  |  | and financial liabilities |  | and financial liabilities |
|  |  |  | US$m |  | US$m |
Opening balance |  |  |  |  | (7 | ) |  | 479 |
Adjustment from transition to IFRS 9 |  |  |  |  | 19 |  |  | - |
Currency translation adjustments |  |  |  |  | (23 | ) |  | 8 |
Total realised gains/(losses) included in: |  |  |  |  |  |  |  |  |
– consolidated sales revenue |  |  |  |  | - |  |  | 1 |
– net operating costs |  |  |  |  | 9 |  |  | (5 | )
Total unrealised gains/(losses) included in: |  |  |  |  |  |  |  |  |
- consolidated sales revenue |  |  |  |  | - |  |  | 17 |
– net operating costs (a) |  |  |  |  | 375 |  |  | (508 | )
Total unrealised gains transferred into other comprehensive income through cash flow hedges |  |  |  |  | 181 |  |  | - |
Additions |  |  |  |  | 67 |  |  | - |
Disposals/maturity of financial instruments |  |  |  |  | (6 | ) |  | (5 | )
Transfers |  |  |  |  | 22 |  |  | 6 |
Closing balance |  |  |  |  | 637 |  |  | (7 | )
Total gains/(losses) for the year included in the income statement for assets and liabilities held at year end |  |  |  |  | 346 |  |  | (491 | )
Commodity price risk [Member] |
Disclosure Of Financial Instruments [Line Items] |
Summary of notional aluminium forward sales contracts embedded in power contracts | The Group is holding the following notional aluminium forward sales contracts embedded in the power contracts:
At 31 December 2018 | Within 1 year | Between 1 and 5 years | Between 5 and 10 years | After 10 years
Notional amount (in tonnes) | 56,481 | 286,666 | 358,416 | 65,548
Notional amount (in US$ millions) | 114 | 634 | 870 | 168
Average hedged rate (in US$ per tonne) | 2,013 | 2,210 | 2,426 | 2,562

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