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5 Risk management (Details 2) ¥ in Thousands, R$ in Thousands, $ in Thousands | 12 Months Ended |
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Dec. 31, 2020 BRL (R$) R$ / $ R$ / ¥ Number | Dec. 31, 2020 USD ($) R$ / $ R$ / ¥ Number | Dec. 31, 2020 JPY (¥) R$ / $ R$ / ¥ Number | Dec. 31, 2019 R$ / $ R$ / ¥
USD |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Exchange rate estimated according to the scenario | R$ / $ |  | 5.1967 | 5.1967 | 5.1967 | 4.0307
Yen |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Exchange rate estimated according to the scenario | R$ / ¥ |  | 0.05043 | 0.05043 | 0.05043 | 0.03715
Scenario I (probable) [member] |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Total effect on net financial result in R$ - gain/(loss) | R$ | [1] | R$ (10,492) |  |  |
Scenario I (probable) [member] | USD |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Net currency exposure | $ | [1] |  | $ 167,479 |  |
Currency rate | [1] | 5.1967 | 5.1967 | 5.1967 |
Exchange rate estimated according to the scenario | [1] | 5.0000 | 5.0000 | 5.0000 |
Differences between the rates | [1] | 0.1967 | 0.1967 | 0.1967 |
Effect on net financial result R$ - gain/(loss) | $ | [1] |  | $ 32,943 |  |
Scenario I (probable) [member] | Yen |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Net currency exposure | ¥ | [1] |  |  | ¥ 52,969,560 |
Currency rate | [1] | 0.05043 | 0.05043 | 0.05043 |
Exchange rate estimated according to the scenario | [1] | 0.05125 | 0.05125 | 0.05125 |
Differences between the rates | [1] | (0.00082) | (0.00082) | (0.00082) |
Effect on net financial result R$ - gain/(loss) | ¥ | [1] |  |  | ¥ (43,435) |
Scenario II (+25%) [member] |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Total effect on net financial result in R$ - gain/(loss) | R$ |  | R$ (898,381) |  |  |
Scenario II (+25%) [member] | USD |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Net currency exposure | $ |  |  | $ 167,479 |  |
Currency rate |  | 5.1967 | 5.1967 | 5.1967 |
Exchange rate estimated according to the scenario |  | 6.2500 | 6.2500 | 6.2500 |
Differences between the rates |  | (1.0533) | (1.0533) | (1.0533) |
Effect on net financial result R$ - gain/(loss) | $ |  |  | $ (176,406) |  |
Scenario II (+25%) [member] | Yen |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Net currency exposure | ¥ |  |  |  | ¥ 52,969,560 |
Currency rate |  | 0.05043 | 0.05043 | 0.05043 |
Exchange rate estimated according to the scenario |  | 0.06406 | 0.06406 | 0.06406 |
Differences between the rates |  | (0.01363) | (0.01363) | (0.01363) |
Effect on net financial result R$ - gain/(loss) | ¥ |  |  |  | ¥ (721,975) |
Scenario III (+50%) [member] |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Total effect on net financial result in R$ - gain/(loss) | R$ |  | R$ (1,786,269) |  |  |
Scenario III (+50%) [member] | USD |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Net currency exposure | $ |  |  | $ 167,479 |  |
Currency rate |  | 5.1967 | 5.1967 | 5.1967 |
Exchange rate estimated according to the scenario |  | 7.5000 | 7.5000 | 7.5000 |
Differences between the rates |  | (2.3033) | (2.3033) | (2.3033) |
Effect on net financial result R$ - gain/(loss) | $ |  |  | $ (385,754) |  |
Scenario III (+50%) [member] | Yen |  |  |  |  |
Summary of risk management [Line Items] |  |  |  |  |
Net currency exposure | ¥ |  |  |  | ¥ 52,969,560 |
Currency rate |  | 0.05043 | 0.05043 | 0.05043 |
Exchange rate estimated according to the scenario |  | 0.07687 | 0.07687 | 0.07687 |
Differences between the rates |  | (0.02644) | (0.02644) | (0.02644) |
Effect on net financial result R$ - gain/(loss) | ¥ |  |  |  | ¥ (1,400,515) |
[1] | For the probable scenario in US dollar, the exchange rate estimated for December 31, 2021 was used, pursuant to the BACEN Focus Report of December 31, 2020. For the Yen, the exchange estimated for December 31, 2021 was used, according to B3's Reference Rates report of December 31, 2020.

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