Risk management (Details 6) - BRL (R$) R$ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Sensibilities [Abstract]
Net Interest Margin	R$ 378	R$ 385	R$ 525
Market Value of Equity	2,066	1,680	1,800
Value at Risk - Balance
VaR	R$ 1,380	R$ 804	R$ 926

The measure of a potential loss exposure as a result of future market movements, based on a specified confidence interval and measurement horizon.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 41
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_41&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_ValueAtRisk
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant