XML 86 R79.htm IDEA: XBRL DOCUMENT
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Concessions and Authorizations - Additional Information (Detail) R$ in Millions |  |  |  | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Sep. 27, 2017 BRL (R$) MW | Aug. 03, 2017 BRL (R$) | Dec. 26, 2014 | Dec. 31, 2017 BRL (R$) | Dec. 31, 2016 BRL (R$) | Dec. 31, 2015 BRL (R$) | Dec. 31, 2014 BRL (R$)
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Investment |  |  |  | R$ 618 | R$ 801 | R$ 861 | R$ 906
Small hydro plants enterprise [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Discount of future payments |  |  |  | 12.50% |  |  |
Conventional hydroelectric plants enterprise [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Discount of future payments |  |  |  | 5.10% |  |  |
2019 [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Percentage of Selic rate |  |  |  | 80.00% |  |  |
2020 [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Percentage of Selic rate |  |  |  | 111.00% |  |  |
Second Amendment to Concession Contract [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Concession contract for electricity generation, additional period |  |  | 30 years |  |  |  |
Original expiration date of concession contract |  |  | Jan. 10, 2023 |  |  |  |
Extended expiration date of concession contract |  |  | Jan. 10, 2053 |  |  |  |
Cemig Distribution [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Concession expired |  |  |  | Dec. 31, 2045 |  |  |
Cemig GT [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Annual generation revenue of plants |  |  |  | R$ 462 | 319 |  |
Residual value of the infrastructure assets |  | R$ 1,028 |  | 1,084 |  |  |
Income from residual value of the infrastructure assets |  | 271 |  |  |  |  |
Investment |  |  |  | 126 | R$ 127 |  |
Cemig GT [member] | Sao Simao Jaguara and Miranda hydroelectric plants [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Plant capacity | MW | 2,922 |  |  |  |  |  |
Sale price of plant | R$ 12,131 |  |  |  |  |  |
Cemig GT [member] | Sao simao hydroelectric plant [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Residual value of the infrastructure assets |  | 244 |  |  |  |  |
Investment |  |  |  | 3 |  |  |
Cemig GT [member] | Miranda hydroelectric plant [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Residual value of the infrastructure assets |  | R$ 784 |  |  |  |  |
Investment |  |  |  | 23 |  |  |
Cemig GT [member] | Jaguara hydroelectric plant [member] |  |  |  |  |  |  |
Disclosure of electricity concessions and authorizations [Line Items] |  |  |  |  |  |  |
Investment |  |  |  | R$ 174 |  |  |

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- Definition Expiry date 2019-01-01: The amount of property (land or a building - or part of a building - or both) held (by the owner or by the lessee under a finance lease) to earn rentals or for capital appreciation or both, rather than for: (a) use in the production or supply of goods or services or for administrative purposes; or (b) sale in the ordinary course of business. Effective 2019-01-01: The amount of property (land or a building - or part of a building - or both) held (by the owner or by the lessee as a right-of-use asset) to earn rentals or for capital appreciation or both, rather than for: (a) use in the production or supply of goods or services or for administrative purposes; or (b) sale in the ordinary course of business. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2017-01-01 -Paragraph 76 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=40&date=2017-03-01&anchor=para_76&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2017-01-01 -Paragraph 79 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=40&date=2017-03-01&anchor=para_79_d&doctype=Standard -URIDate 2017-03-09 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 54 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_54_b&doctype=Standard -URIDate 2017-03-09 + Details
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