XML 205 R198.htm IDEA: XBRL DOCUMENT v3.8.0.1

Financial Instruments and Risk Management - Summary of Changes in Value of Options (Detail) - BRL (R$) R$ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of financial liabilities [line items]
Variation in fair value	R$ 187
Put option - SAAG [member]
Disclosure of financial liabilities [line items]
Balance	196	R$ 148	R$ 29
Variation in fair value	121
Adjustment to fair value		48	119
Reversals	(5)
Balance	R$ 312	R$ 196	R$ 148

X

- Definition

The amount of financial liabilities classified as derivative instruments. [Refer: Financial assets; Derivatives [member]]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_55&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_DerivativeFinancialLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfFinancialLiabilitiesLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The increase (decrease) in the fair value measurement of liabilities. [Refer: At fair value [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 13
-IssueDate 2017-01-01
-Paragraph 93
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=13&date=2017-03-01&anchor=para_93_e&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_IncreaseDecreaseInFairValueMeasurementLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Adjustment to fair value of options.

+ References

No definition available.

+ Details

Name:	xcmig_AdjustmentToFairValueOfOptions
Namespace Prefix:	xcmig_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Reversals derivative financial liabilities.

+ References

No definition available.

+ Details

Name:	xcmig_ReversalsDerivativeFinancialLiabilities
Namespace Prefix:	xcmig_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	ifrs-full_ClassesOfFinancialInstrumentsAxis=xcmig_PutOptionSAAGMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: