22. Equity (Details 3) - BRL (R$) R$ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SummaryOfEquityLineItems [Line Items]
Other comprehensive loss, beginning	R$ (825,648)
Actuarial gains/(losses) for the year	(287,547)	R$ 472,266	R$ (36,366)
Other comprehensive loss, ending	(538,101)	(825,648)
Funded plan - G1
SummaryOfEquityLineItems [Line Items]
Other comprehensive loss, beginning	(165,085)
Actuarial gains/(losses) for the year	236,012
Other comprehensive loss, ending	70,927	(165,085)
Unfunded plan
SummaryOfEquityLineItems [Line Items]
Other comprehensive loss, beginning	(660,563)
Actuarial gains/(losses) for the year	51,535	(241,711)
Other comprehensive loss, ending	R$ (609,028)	R$ (660,563)

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)]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2017-01-01
-Paragraph 141
-Subparagraph c
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_141_c_iii&doctype=Standard
-URIDate 2017-03-09

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration