The amount of assets representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognised. [Refer: Business combinations [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2017-01-01
-Paragraph B67
-Subparagraph d
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Balance Type:	debit
Period Type:	instant

GOODWILL - Goodwill by segment (Details) - BRL (R$) R$ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill by segment
Goodwill	R$ 7,891,142	R$ 9,470,016	R$ 15,124,430	R$ 12,556,404
Brazil
Goodwill by segment
Goodwill	373,135	380,644	519,327
Special Steel
Goodwill by segment
Goodwill	2,487,364	2,508,056	3,409,429
North America
Goodwill by segment
Goodwill	R$ 5,030,643	R$ 6,581,316	R$ 11,195,674