Condensed Consolidating Financial Information - CASH FLOWS (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Cash Flows from Operating Activities
Net (Loss)/Income	$ (48)	$ 163	$ 281	$ (682)
Loss from discontinued operations	(354)	(22)	(320)	(798)
Net income	306	185	601	116
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Distributions and equity in earnings of unconsolidated affiliates			10	0
Depreciation, amortization and accretion			403	490
Provision for bad debts			57	57
Amortization of nuclear fuel			38	37
Amortization of financing costs and debt discount/premiums			21	15
Adjustment for debt extinguishment			22	3
Amortization of intangibles and out-of-market contracts			21	79
Amortization of unearned equity compensation			36	27
Impairment losses			89	60
Changes in deferred income taxes and liability for uncertain tax benefits			(6)	(1)
Changes in nuclear decommissioning trust liability			50	20
Changes in derivative instruments			(17)	36
Changes in collateral deposits in support of energy risk management activities			(30)	(103)
Gain on sale of emission allowances			(20)	21
Gain on sale of assets	(14)		(30)	(4)
GenOn settlement in July 2018			(125)	0
Loss on deconsolidation of business			13	0
Changes in other working capital			(375)	(295)
Cash provided/(used) by continuing operations			758	558
Cash provided by discontinued operations			324	178
Net Cash Provided/(Used) by Operating Activities			1,082	736
Cash Flows from Investing Activities
Intercompany dividends				0
Acquisitions of businesses, net of cash acquired			(209)	(12)
Capital expenditures			(345)	(172)
Purchases of emission allowances			(30)	(47)
Proceeds from sale of emission allowances			54	104
Investments in nuclear decommissioning trust fund securities			(449)	(402)
Proceeds from the sale of nuclear decommissioning trust fund securities			398	382
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees			1,555	309
Deconsolidation of business			(268)	0
Change in investments in unconsolidated affiliates			(62)	24
Other			0	30
Cash (used)/provided by continuing operations			644	216
Cash used by discontinued operations			(703)	(638)
Net Cash (Used)/Provided by Investing Activities			(59)	(422)
Cash Flows from Financing Activities
Payments (for)/from intercompany loans			0	0
Intercompany dividends				0
Payment of dividends to common stockholders			(28)	(28)
Payment for treasury stock			(1,000)	0
Net receipts from settlement of acquired derivatives that include financing elements				0
Proceeds from issuance of long-term debt			995	308
Payments for short and long-term debt			(970)	(343)
Increase in notes receivable from affiliate			(26)	(125)
Net distributions to noncontrolling interests in subsidiaries			(17)	(18)
Payment of debt issuance costs			(19)	(39)
Other			(4)	(8)
Cash provided/(used) by continuing operations			(1,069)	(253)
Cash provided by discontinued operations			403	39
Net Cash Provided/(Used) by Financing Activities			(666)	(214)
Effect of exchange rate changes on cash and cash equivalents			1	(10)
Change in Cash from discontinued operations			24	(421)
Net Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash			334	511
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			1,083	860
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	1,417	1,371	1,417	1,371
Eliminations
Cash Flows from Operating Activities
Net (Loss)/Income	(399)	(500)	(1,095)	(827)
Loss from discontinued operations	0	0	0	0
Net income	(399)	(500)	(1,095)	(827)
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Distributions and equity in earnings of unconsolidated affiliates			0	62
Depreciation, amortization and accretion			0	0
Provision for bad debts			0	0
Amortization of nuclear fuel			0	0
Amortization of financing costs and debt discount/premiums			0	0
Adjustment for debt extinguishment			0	0
Amortization of intangibles and out-of-market contracts			0	0
Amortization of unearned equity compensation			0	0
Impairment losses			0	0
Changes in deferred income taxes and liability for uncertain tax benefits			0	0
Changes in nuclear decommissioning trust liability			0	0
Changes in derivative instruments			(15)	(8)
Changes in collateral deposits in support of energy risk management activities			0	0
Gain on sale of emission allowances			0	0
Gain on sale of assets			0	0
GenOn settlement in July 2018			0
Loss on deconsolidation of business			0
Changes in other working capital			1,110	773
Cash provided/(used) by continuing operations			0	0
Cash provided by discontinued operations			0	0
Net Cash Provided/(Used) by Operating Activities			0	0
Cash Flows from Investing Activities
Intercompany dividends				(129)
Acquisitions of businesses, net of cash acquired			0	0
Capital expenditures			0	0
Purchases of emission allowances			0	0
Proceeds from sale of emission allowances			0	0
Investments in nuclear decommissioning trust fund securities			0	0
Proceeds from the sale of nuclear decommissioning trust fund securities			0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees			0	0
Deconsolidation of business			0
Change in investments in unconsolidated affiliates			0	0
Other				0
Cash (used)/provided by continuing operations			0	(129)
Cash used by discontinued operations				0
Net Cash (Used)/Provided by Investing Activities			0	(129)
Cash Flows from Financing Activities
Payments (for)/from intercompany loans			0	0
Intercompany dividends				129
Payment of dividends to common stockholders			0	0
Payment for treasury stock			0
Net receipts from settlement of acquired derivatives that include financing elements				0
Proceeds from issuance of long-term debt			0	0
Payments for short and long-term debt			0	0
Increase in notes receivable from affiliate				0
Net distributions to noncontrolling interests in subsidiaries			0	0
Payment of debt issuance costs			0	0
Other			0	0
Cash provided/(used) by continuing operations			0	129
Cash provided by discontinued operations			0	0
Net Cash Provided/(Used) by Financing Activities			0	129
Effect of exchange rate changes on cash and cash equivalents			0	0
Change in Cash from discontinued operations			0	0
Net Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash			0	0
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			0	0
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	0	0	0	0
Guarantor Subsidiaries
Cash Flows from Operating Activities
Net (Loss)/Income	306	342	849	737
Loss from discontinued operations	0	0	0	0
Net income	306	342	849	737
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Distributions and equity in earnings of unconsolidated affiliates			0	0
Depreciation, amortization and accretion			240	299
Provision for bad debts			55	42
Amortization of nuclear fuel			38	37
Amortization of financing costs and debt discount/premiums			0	0
Adjustment for debt extinguishment			0	0
Amortization of intangibles and out-of-market contracts			15	20
Amortization of unearned equity compensation			0	0
Impairment losses			0	42
Changes in deferred income taxes and liability for uncertain tax benefits			343	0
Changes in nuclear decommissioning trust liability			50	20
Changes in derivative instruments			(38)	(11)
Changes in collateral deposits in support of energy risk management activities			(16)	(126)
Gain on sale of emission allowances			(20)	21
Gain on sale of assets			(3)	(4)
GenOn settlement in July 2018			0
Loss on deconsolidation of business			0
Changes in other working capital			(567)	(1,035)
Cash provided/(used) by continuing operations			946	42
Cash provided by discontinued operations			0	0
Net Cash Provided/(Used) by Operating Activities			946	42
Cash Flows from Investing Activities
Intercompany dividends				0
Acquisitions of businesses, net of cash acquired			(2)	0
Capital expenditures			(158)	(135)
Purchases of emission allowances			(30)	(47)
Proceeds from sale of emission allowances			54	105
Investments in nuclear decommissioning trust fund securities			(449)	(402)
Proceeds from the sale of nuclear decommissioning trust fund securities			398	382
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees			10	36
Deconsolidation of business			0
Change in investments in unconsolidated affiliates			0	0
Other				30
Cash (used)/provided by continuing operations			(177)	(31)
Cash used by discontinued operations			0	0
Net Cash (Used)/Provided by Investing Activities			(177)	(31)
Cash Flows from Financing Activities
Payments (for)/from intercompany loans			(645)	9
Intercompany dividends				0
Payment of dividends to common stockholders			0	0
Payment for treasury stock			0
Net receipts from settlement of acquired derivatives that include financing elements				0
Proceeds from issuance of long-term debt			0	0
Payments for short and long-term debt			0	0
Increase in notes receivable from affiliate			0	0
Net distributions to noncontrolling interests in subsidiaries			0	0
Payment of debt issuance costs			0	0
Other			0	0
Cash provided/(used) by continuing operations			(645)	9
Cash provided by discontinued operations			0	0
Net Cash Provided/(Used) by Financing Activities			(645)	9
Effect of exchange rate changes on cash and cash equivalents			0	0
Change in Cash from discontinued operations			0	0
Net Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash			124	20
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			41	3
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	165	23	165	23
Non-Guarantor Subsidiaries
Cash Flows from Operating Activities
Net (Loss)/Income	105	121	140	(28)
Loss from discontinued operations	17	12	77	(134)
Net income	88	109	63	106
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Distributions and equity in earnings of unconsolidated affiliates			9	(65)
Depreciation, amortization and accretion			138	167
Provision for bad debts			2	0
Amortization of nuclear fuel			0	0
Amortization of financing costs and debt discount/premiums			5	2
Adjustment for debt extinguishment			0	3
Amortization of intangibles and out-of-market contracts			6	59
Amortization of unearned equity compensation			0	0
Impairment losses			89	18
Changes in deferred income taxes and liability for uncertain tax benefits			11	(7)
Changes in nuclear decommissioning trust liability			0	0
Changes in derivative instruments			40	43
Changes in collateral deposits in support of energy risk management activities			(14)	23
Gain on sale of emission allowances			0	0
Gain on sale of assets			(27)	0
GenOn settlement in July 2018			0
Loss on deconsolidation of business			13
Changes in other working capital			(61)	(484)
Cash provided/(used) by continuing operations			274	(135)
Cash provided by discontinued operations			324	178
Net Cash Provided/(Used) by Operating Activities			598	43
Cash Flows from Investing Activities
Intercompany dividends				0
Acquisitions of businesses, net of cash acquired			(207)	(12)
Capital expenditures			(150)	(18)
Purchases of emission allowances			0	0
Proceeds from sale of emission allowances			0	(1)
Investments in nuclear decommissioning trust fund securities			0	0
Proceeds from the sale of nuclear decommissioning trust fund securities			0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees			8	0
Deconsolidation of business			(268)
Change in investments in unconsolidated affiliates			(62)	24
Other				0
Cash (used)/provided by continuing operations			(679)	(7)
Cash used by discontinued operations			(703)	(638)
Net Cash (Used)/Provided by Investing Activities			(1,382)	(645)
Cash Flows from Financing Activities
Payments (for)/from intercompany loans			(12)	417
Intercompany dividends				(129)
Payment of dividends to common stockholders			0	0
Payment for treasury stock			0
Net receipts from settlement of acquired derivatives that include financing elements				0
Proceeds from issuance of long-term debt			163	94
Payments for short and long-term debt			(106)	(124)
Increase in notes receivable from affiliate			0	(125)
Net distributions to noncontrolling interests in subsidiaries			(17)	(18)
Payment of debt issuance costs			0	(34)
Other			(4)	(8)
Cash provided/(used) by continuing operations			24	73
Cash provided by discontinued operations			403	39
Net Cash Provided/(Used) by Financing Activities			427	112
Effect of exchange rate changes on cash and cash equivalents			1	(10)
Change in Cash from discontinued operations			24	(421)
Net Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash			(380)	(79)
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			399	534
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	19	455	19	455
NRG Energy, Inc. (Note Issuer)
Cash Flows from Operating Activities
Net (Loss)/Income	(60)	200	387	(564)
Loss from discontinued operations	(371)	(34)	(397)	(664)
Net income	311	234	784	100
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Distributions and equity in earnings of unconsolidated affiliates			1	3
Depreciation, amortization and accretion			25	24
Provision for bad debts			0	15
Amortization of nuclear fuel			0	0
Amortization of financing costs and debt discount/premiums			16	13
Adjustment for debt extinguishment			22	0
Amortization of intangibles and out-of-market contracts			0	0
Amortization of unearned equity compensation			36	27
Impairment losses			0	0
Changes in deferred income taxes and liability for uncertain tax benefits			(360)	6
Changes in nuclear decommissioning trust liability			0	0
Changes in derivative instruments			(4)	12
Changes in collateral deposits in support of energy risk management activities			0	0
Gain on sale of emission allowances			0	0
Gain on sale of assets			0	0
GenOn settlement in July 2018			(125)
Loss on deconsolidation of business			0
Changes in other working capital			(857)	451
Cash provided/(used) by continuing operations			(462)	651
Cash provided by discontinued operations			0	0
Net Cash Provided/(Used) by Operating Activities			(462)	651
Cash Flows from Investing Activities
Intercompany dividends				129
Acquisitions of businesses, net of cash acquired			0	0
Capital expenditures			(37)	(19)
Purchases of emission allowances			0	0
Proceeds from sale of emission allowances			0	0
Investments in nuclear decommissioning trust fund securities			0	0
Proceeds from the sale of nuclear decommissioning trust fund securities			0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees			1,537	273
Deconsolidation of business			0
Change in investments in unconsolidated affiliates			0	0
Other				0
Cash (used)/provided by continuing operations			1,500	383
Cash used by discontinued operations				0
Net Cash (Used)/Provided by Investing Activities			1,500	383
Cash Flows from Financing Activities
Payments (for)/from intercompany loans			657	(426)
Intercompany dividends				0
Payment of dividends to common stockholders			(28)	(28)
Payment for treasury stock			(1,000)
Net receipts from settlement of acquired derivatives that include financing elements				0
Proceeds from issuance of long-term debt			832	214
Payments for short and long-term debt			(864)	(219)
Increase in notes receivable from affiliate			(26)	0
Net distributions to noncontrolling interests in subsidiaries			0	0
Payment of debt issuance costs			(19)	(5)
Other			0	0
Cash provided/(used) by continuing operations			(448)	(464)
Cash provided by discontinued operations			0	0
Net Cash Provided/(Used) by Financing Activities			(448)	(464)
Effect of exchange rate changes on cash and cash equivalents			0	0
Change in Cash from discontinued operations			0	0
Net Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash			590	570
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			643	323
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	$ 1,233	$ 893	$ 1,233	$ 893

The aggregate (income) expense recorded in earnings to allocate the cost of out-of-market contracts and intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash (income) expense, this element is added back to net income when calculating cash provided by (used in) operations using the indirect method.

No definition available.