Commitments and Contingencies (Details) - USD ($)	1 Months Ended	6 Months Ended
	Aug. 31, 2009	Jun. 30, 2017	Dec. 13, 2016
Midwest Generation New Source Review
Loss Contingencies
Damages sought, amount	$ 37,500
Telephone Consumer Protection Act Purported Class Actions
Loss Contingencies
Damages sought, amount		$ 1,500
CDWR and SDGE v Sunrise Power
Loss Contingencies
Damages sought, amount		$ 1,200,000
Remaining term		70 months
Texas Westmoreland Coal Co. [Member] | Lignite Contract with Texas Westmoreland Coal Co.
Loss Contingencies
Bond obligation		$ 95,500,000
Senior Notes | Senior Unsecured Notes 2021 | GenOn Americas Generation, LLC
Loss Contingencies
Interest rate, stated percentage			8.50%
Senior Notes | Senior Unsecured Notes 2017 | GenOn Energy
Loss Contingencies
Interest rate, stated percentage			7.875%
Senior Notes | Senior Unsecured Notes 2031 | GenOn Americas Generation, LLC
Loss Contingencies
Interest rate, stated percentage			9.125%
Senior Notes | Senior Unsecured Notes 2018 | GenOn Energy
Loss Contingencies
Interest rate, stated percentage			9.50%
Senior Notes | Senior Unsecured Notes 2020 | GenOn Energy
Loss Contingencies
Interest rate, stated percentage			9.875%