Subsequent Events	6 Months Ended
Subsequent Events	Jun. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Direct Energy Acquisition On July 24, 2020, the Company entered into a definitive purchase agreement with Centrica to acquire Direct Energy, a North American subsidiary of Centrica (the "Purchase Agreement"). Direct Energy is a leading retail provider of electricity, natural gas, and home and business energy related products and services in North America, with operations in all 50 U.S. states and 6 Canadian provinces. The acquisition will add over 3 million customers to NRG's business and build on and complement its integrated model, enabling better matching of power generation with customer demand. It will also broaden the Company's presence in the Northeast and into states and locales where it does not currently operate, supporting NRG's objective to diversify its business. The Company will pay an aggregate purchase price of $3.6 billion in cash, subject to a purchase price adjustment, including a working capital adjustment. The Company expects to fund the purchase price using a combination of cash on hand, approximately $2.4 billion in newly-issued secured and unsecured corporate debt and approximately $750 million in convertible preferred stock or other equity-linked instruments. The Company also expects to increase its collective collateral facilities by $3.5 billion through a combination of new letter of credit facilities and increase to the existing Revolving Credit Facility. The acquisition is subject to approval by the shareholders of Centrica, as well as customary closing conditions, consents and regulatory approvals, including the expiration or termination of the applicable waiting period under the HSR Act, and the receipt of approvals or expiration of applicable waiting periods under the Federal Power Act and the Canadian Competition Act. The acquisition is targeted to close by December 31, 2020. There are no assurances that the conditions to the consummation of the acquisition of Direct Energy will be satisfied, that Centrica will not seek or enter into an alternative transaction as discussed below, or that the acquisition of Direct Energy will be consummated on the terms agreed to, or at all. Prior to the approval of the transaction by its shareholders, Centrica is permitted to respond to unsolicited acquisition proposals that constitute or are reasonably likely to lead to a superior proposal, and to engage in negotiations with, and provide information to, parties that submit these proposals. Centrica can terminate the Purchase Agreement to accept a superior proposal. In addition, the board of directors of Centrica can change its recommendation in favor of NRG's transaction if the failure to do so would be inconsistent with the fiduciary duties of the Centrica directors, in which case the Purchase Agreement would automatically terminate. In the event of a termination of the Purchase Agreement in connection with (i) Centrica's decision to accept a superior proposal, (ii) the failure to obtain Centrica shareholder approval, or (iii) a change of recommendation by the Centrica board, Centrica would be obligated to pay NRG a termination fee of approximately $30 million. NRG will be required to pay Centrica a termination fee of $180 million if the Purchase Agreement is terminated (i) by either Centrica or NRG because the transaction has not been completed by July 24, 2021 (as such date may be extended for two separate three month periods if necessary to obtain required regulatory approvals, through January 24, 2022), and at the time of termination all of the mutual conditions to the obligations of NRG and Centrica to close the acquisition, and all the conditions to NRG's obligations to close the acquisition, have been satisfied other than receipt of the required antitrust and competition approvals, (ii) by either Centrica or NRG if a governmental entity has issued a judgment with respect to an antitrust or competition law that permanently prohibits the completion of the transaction and the judgment has become final and non-appealable, (iii) by NRG if a governmental entity has imposed a condition on its willingness to approve the acquisition on antitrust or competition grounds and the condition has a material adverse effect as described in the Purchase Agreement or (iv) by Centrica because NRG has breached its obligations under the Purchase Agreement to seek to obtain the antitrust and competition approvals required to complete the transaction. Midwest Generation Lease Purchase On July 22, 2020, Midwest Generation signed purchase agreements to acquire all of the ownership interests in the Powerton facility and Units 7 and 8 of the Joliet facility, which were being leased through 2034 and 2030, respectively, for approximately $260 million. The Company intends to fund the purchase with borrowings under its Revolving Credit Facility in an amount equal to the existing operating lease liabilities of $148 million as of June 30, 2020 and the remainder from cash-on-hand. The closing is conditioned, among other items, on the receipt of regulatory approvals from FERC and under the HSR Act.