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Fair Value of Financial Instruments - Summary of Sensitivity Analyses Operations of Level 3 (Detail) - BRL (R$) R$ in Millions | Dec. 31, 2018 | Dec. 31, 2017
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Interest rate risk [Member] | Scenarios I [Member] |  |
Disclosure of Fair Value Financial Sensitivity Analysis [Line Items] |  |
Impact, Result | R$ (0.4) | R$ (1.9)
Impact, Stockholders' equity | (1.2) | (2.4)
Interest rate risk [Member] | Scenarios II [Member] |  |
Disclosure of Fair Value Financial Sensitivity Analysis [Line Items] |  |
Impact, Result | (9.3) | (47.0)
Impact, Stockholders' equity | (29.3) | (55.4)
Interest rate risk [Member] | Scenarios III [Member] |  |
Disclosure of Fair Value Financial Sensitivity Analysis [Line Items] |  |
Impact, Result | (18.6) | (93.9)
Impact, Stockholders' equity | (57.8) | (114.5)
Shares [member] | Scenarios I [Member] |  |
Disclosure of Fair Value Financial Sensitivity Analysis [Line Items] |  |
Impact, Result | (63.4) | (146.6)
Shares [member] | Scenarios II [Member] |  |
Disclosure of Fair Value Financial Sensitivity Analysis [Line Items] |  |
Impact, Result | (126.8) | (293.2)
Nonlinear [Member] | Scenarios I [Member] |  |
Disclosure of Fair Value Financial Sensitivity Analysis [Line Items] |  |
Impact, Result | (48.2) | (9.2)
Nonlinear [Member] | Scenarios II [Member] |  |
Disclosure of Fair Value Financial Sensitivity Analysis [Line Items] |  |
Impact, Result | R$ (89.3) | R$ (11.9)

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