Schedule of changes in net liabilities (Details) - BRL (R$) R$ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
IfrsStatementLineItems [Line Items]
Net liabilities at December 31, 2020	R$ 6,843	R$ 6,709	R$ 4,989
Expense recognized in Statement of income	501	491	464
Contributions paid	(422)	(367)	(343)
Actuarial gains (losses)	(302)	10	1,599
Past service cost (1)	(415)
Net liabilities at December 31, 2021	6,205	6,843	6,709
Current liabilities	305
Non-currentliabilities	6,538
Pension Plans And Retirement Supplement Plans [member]
IfrsStatementLineItems [Line Items]
Net liabilities at December 31, 2020	2,909	2,972	2,170
Expense recognized in Statement of income	200	206	197
Contributions paid	(236)	(211)	(200)
Actuarial gains (losses)	(203)	(58)	805
Past service cost (1)
Net liabilities at December 31, 2021	2,670	2,909	2,972
Health Plan [member]
IfrsStatementLineItems [Line Items]
Net liabilities at December 31, 2020	3,319	3,102	2,344
Expense recognized in Statement of income	253	236	222
Contributions paid	(173)	(143)	(131)
Actuarial gains (losses)	70	124	667
Past service cost (1)
Net liabilities at December 31, 2021	3,469	3,319	3,102
Dental Plan [member]
IfrsStatementLineItems [Line Items]
Net liabilities at December 31, 2020	64	61	48
Expense recognized in Statement of income	6	5	5
Contributions paid	(3)	(3)	(2)
Actuarial gains (losses)	(1)	1	10
Past service cost (1)
Net liabilities at December 31, 2021	66	64	61
life insurance [member]
IfrsStatementLineItems [Line Items]
Net liabilities at December 31, 2020	551	574	427
Expense recognized in Statement of income	42	44	40
Contributions paid	(10)	(10)	(10)
Actuarial gains (losses)	(168)	(57)	117
Past service cost (1)	(415)
Net liabilities at December 31, 2021		R$ 551	R$ 574
Current liabilities	347
Non-currentliabilities	R$ 5,858

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The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in financial assumptions that result in remeasurements of the net defined benefit liability (asset). Financial assumptions deal with items such as: (a) the discount rate; (b) benefit levels, excluding any cost of the benefits to be met by employees, and future salary; (c) in the case of medical benefits, future medical costs, including claim handling costs (ie the costs that will be incurred in processing and resolving claims, including legal and adjuster's fees); and (d) taxes payable by the plan on contributions relating to service before the reporting date or on benefits resulting from that service. [Refer: Net defined benefit liability (asset)]

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The amount of employer contributions to retirement benefit plans.

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The fair value of any plan assets, less the present value of the defined benefit obligation. [Refer: Plan assets [member]]

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