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Taxes - Summary of Calculation of Tax Rates (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of effective income tax rate [Line Items]
Social contribution of tax rate	20.00%	15.00%
Financial institutions [member] | Bottom of range [member]
Disclosure of effective income tax rate [Line Items]
Social contribution of tax rate	15.00%
Financial institutions [member] | Top of range [member]
Disclosure of effective income tax rate [Line Items]
Social contribution of tax rate	20.00%
Other companies [member]
Disclosure of effective income tax rate [Line Items]
Social contribution of tax rate	9.00%

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- Definition

Line items represent effective income tax rate.

+ References

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- Definition

Social contribution tax rate.

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