XML 198 R191.htm IDEA: XBRL DOCUMENT v3.19.1
Provisions - Additional Information (Detail) - BRL (R$)
R$ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Disclosure of provisions and contingencies [line items]    
Description of contingencies Cemig and Cemig D are defendants in several public civil claims (class actions) requesting nullity of the clause in the Electricity Supply Contracts for public illumination signed between the Company and the various municipalities of its concession area, and restitution by the Company of the difference representing the amounts charged in the last 20 years, in the event that the courts recognize that these amounts were unduly charged.  
Estimated legal and other disputes based on non-compliance of contracts R$ 90 R$ 80
Employees [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 304 311
Indemnity Liabilities 178  
Indemnity liabilities court permitted payment into court 122  
Indemnity liabilities court permitted payment into court updated represents amount 275 267
Social Security Contributions [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 1,420 1,334
Non homologation of offsetting of tax credit [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount R$ 146 275
Corporate tax return restitution and offsetting [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount   576
Parati [member]    
Disclosure of provisions and contingencies [line items]    
Equity interest 100.00%  
Luce brasil equity investment fund [member]    
Disclosure of provisions and contingencies [line items]    
Equity interest 75.00%  
Light SA [member]    
Disclosure of provisions and contingencies [line items]    
Voting shares percentage 13.03%  
Income tax withheld at sourced on capital gain in stockholding transaction [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount R$ 221 212
Social contribution tax on net income [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 350 322
Aneel Normative Resolution 456/2000 [member]    
Disclosure of provisions and contingencies [line items]    
Contingent provision 975 1,224
Accounting of electricity sale transactions in electricity trading chamber [member]    
Disclosure of provisions and contingencies [line items]    
Expense on purchase of energy 317 288
System service charges resolution of national energy policy council [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 225 202
Tariff increases [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 303 275
Higher Appeal Court And Federal Supreme Court [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 148 127
Contingent provision 0  
Early settlement of earnings compensation account [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 412 398
Luz Para Todos [member]    
Disclosure of provisions and contingencies [line items]    
Losses on breach of contract 291 261
Provision on losses 0  
Labor claims [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 1,725 1,854
Contingent provision 457 474
Customers claims [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 66 56
Contingent provision 19 19
Other civil actions [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 277 218
Contingent provision 29 43
Contingent provision 36 32
Tax [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 160 159
Contingent provision 46 44
IPTU Urban Land Tax to real estate properties [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 142 122
Contingent provision 5 13
Environment [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 15 68
Amount recognized for settlement of disputes 1  
Regulatory [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 260 222
Contingent provision 37 40
Other [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount 189 196
Contingent provision 11 14
Minas Gerias Brazil [member]    
Disclosure of provisions and contingencies [line items]    
Estimated contingent amount R$ 87 R$ 79
Percentage of annual gross operating revenue to be invested 0.50%  
Description of municipalities involved Emborcação, Pissarrão, Funil, Volta Grande, Poquim, Paraúna, Miranda, Nova Ponte, Rio de Pedras and Peti plants in environmental protection and preservation of the water tables of the counties where these power plants are located,