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Post-Retirement Obligation- Summary of Sensitivity Analysis of the Effects of Changes in the Principal Actuarial Assumptions Used to Determine the Defined-benefit Obligation (Detail) R$ in Millions | Dec. 31, 2017 BRL (R$)
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Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Reduction of one year in the mortality table | R$ 294
Increase of one year in the mortality table | 15
Reduction of 1% in the discount rate | 1,395
Pension plans and retirement supplement plans [member] |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Reduction of one year in the mortality table | 273
Reduction of 1% in the discount rate | 1,103
Health plan [member] |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Reduction of one year in the mortality table | 36
Reduction of 1% in the discount rate | 244
Dental plan [member] |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Reduction of one year in the mortality table | 1
Reduction of 1% in the discount rate | 5
Life insurance [member] |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |
Reduction of one year in the mortality table | (16)
Increase of one year in the mortality table | 15
Reduction of 1% in the discount rate | R$ 43

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- Definition The increase (decrease) in a defined benefit obligation that would have been caused by a decrease in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 145 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_145_a&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The increase (decrease) in a defined benefit obligation that would have been caused by an increase in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 145 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_145_a&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition Reduction of one percent in discount rate. + References No definition available. + Details
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