Document and Entity Information	9 Months Ended
	Sep. 30, 2017 shares
Document and Entity Information [Line Items]
Entity Registrant Name	GenOn Energy, Inc.
Entity Central Index Key	0001126294
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding	0
GenOn Americas Generation, LLC
Document and Entity Information [Line Items]
Entity Registrant Name	GenOn Americas Generation, LLC
Entity Central Index Key	0001140761
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Entity Common Stock, Shares Outstanding	0
GenOn Mid-Atlantic, LLC
Document and Entity Information [Line Items]
Entity Registrant Name	GenOn Mid-Atlantic, LLC
Entity Central Index Key	0001138258
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Entity Common Stock, Shares Outstanding	0