Talen Energy Supply 10-Q 9 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 30, 2015
Entity Registrant Name	TALEN ENERGY CORPORATION
Entity Central Index Key	1,622,536
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		128,508,921
Talen Energy Supply
Entity Registrant Name	TALEN ENERGY SUPPLY, LLC
Entity Central Index Key	1,161,976
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		0

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating Revenues
Wholesale energy	$ 986	$ 1,109	$ 2,181	$ 203
Wholesale energy to affiliate	0	20	14	68
Retail energy	277	283	831	913
Energy-related businesses	156	189	404	469
Total Operating Revenues	1,419	1,601	3,430	1,653
Operation
Fuel	394	212	945	953
Energy purchases	298	708	588	(893)
Operation and maintenance	228	232	759	746
Impairments	479	0	479	0
Depreciation	95	74	259	225
Taxes, other than income	19	14	49	45
Energy-related businesses	152	172	385	451
Total Operating Expenses	1,665	1,412	3,464	1,527
Operating Income (Loss)	(246)	189	(34)	126
Other Income (Expense) - net	1	10	11	23
Interest Expense	55	31	146	95
Income (Loss) from Continuing Operations Before Income Taxes	(300)	168	(169)	54
Income Taxes	39	74	49	16
Income (Loss) from Continuing Operations After Income Taxes	(339)	94	(218)	38
Income (Loss) from Discontinued Operations (net of income taxes)	(62)	7	(61)	10
Net Income (Loss)	$ (401)	$ 101	$ (279)	$ 48
Earnings Per Share of Common Stock - Basic:
Income (Loss) from continuing operations after income taxes (in dollars per share)	$ (2.64)	$ 1.13	$ (2.10)	$ 0.45
Income (Loss) from discontinued operations (net of income taxes) (in dollars per share)	(0.48)	0.08	(0.59)	0.12
Net Income (Loss) (in dollars per share)	(3.12)	1.21	(2.69)	0.57
Earnings Per Share of Common Stock - Diluted:
Income (Loss) from continuing operations (in dollars per share)	(2.64)	1.13	(2.10)	0.45
Income (Loss) from discontinued operations (net of income taxes) (in dollars per share)	(0.48)	0.08	(0.59)	0.12
Net Income (Loss) (in dollars per share)	$ (3.12)	$ 1.21	$ (2.69)	$ 0.57
Weighted-Average Shares of Common Stock Outstanding (in thousands)
Basic (in shares)	128,509	83,524	103,627	83,524
Diluted (in shares)	128,509	83,524	103,627	83,524
Talen Energy Supply
Operating Revenues
Wholesale energy	$ 986	$ 1,109	$ 2,181	$ 203
Wholesale energy to affiliate	0	20	14	68
Retail energy	277	283	831	913
Energy-related businesses	156	189	404	469
Total Operating Revenues	1,419	1,601	3,430	1,653
Operation
Fuel	394	212	945	953
Energy purchases	298	708	588	(893)
Operation and maintenance	228	232	759	746
Impairments	479	0	479	0
Depreciation	95	74	259	225
Taxes, other than income	19	14	49	45
Energy-related businesses	152	172	385	451
Total Operating Expenses	1,665	1,412	3,464	1,527
Operating Income (Loss)	(246)	189	(34)	126
Other Income (Expense) - net	1	10	11	23
Interest Expense	55	31	146	95
Income (Loss) from Continuing Operations Before Income Taxes	(300)	168	(169)	54
Income Taxes	39	74	49	16
Income (Loss) from Continuing Operations After Income Taxes	(339)	94	(218)	38
Income (Loss) from Discontinued Operations (net of income taxes)	(62)	7	(61)	10
Net Income (Loss)	$ (401)	$ 101	$ (279)	$ 48

CONDENSED CONSOLIDATED STATEME3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net income (loss)	$ (401)	$ 101	$ (279)	$ 48
Amounts arising during the period - gains (losses), net of tax (expense) benefit:
Available-for-sale securities, net of tax	(22)	(1)	(21)	18
Defined benefit plans:
Prior service costs, net of tax	(1)	0	(4)	0
Net actuarial gain, net of tax	0	0	46	0
Reclassifications from AOCI - (gains) losses, net of tax expense (benefit):
Available-for-sale securities, net of tax	1	(3)	(1)	(5)
Qualifying derivatives, net of tax	(4)	(5)	(14)	(18)
Defined benefit plans:
Prior service costs, net of tax	0	1	(1)	2
Net actuarial loss, net of tax	3	1	12	4
Total other comprehensive income (loss)	(23)	(7)	17	1
Comprehensive income (loss)	(424)	94	(262)	49
Talen Energy Supply
Net income (loss)	(401)	101	(279)	48
Amounts arising during the period - gains (losses), net of tax (expense) benefit:
Available-for-sale securities, net of tax	(22)	(1)	(21)	18
Defined benefit plans:
Prior service costs, net of tax	(1)	0	(4)	0
Net actuarial gain, net of tax	0	0	46	0
Reclassifications from AOCI - (gains) losses, net of tax expense (benefit):
Available-for-sale securities, net of tax	1	(3)	(1)	(5)
Qualifying derivatives, net of tax	(4)	(5)	(14)	(18)
Defined benefit plans:
Prior service costs, net of tax	0	1	(1)	2
Net actuarial loss, net of tax	3	1	12	4
Total other comprehensive income (loss)	(23)	(7)	17	1
Comprehensive income (loss)	$ (424)	$ 94	$ (262)	$ 49

CONDENSED CONSOLIDATED STATEME4

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Tax effect of available for sale securities arising during the period	$ 24	$ 1	$ 23	$ (20)
Tax effect of prior service costs for defined benefit plans	0	0	2	0
Tax effect of net actuarial gain for defined benefit plans	0	0	(30)	0
Tax effect of available-for-sale securities reclassified from accumulated other comprehensive income (loss)	0	4	2	6
Tax effect of qualifying derivatives reclassified from accumulated other comprehensive income (loss)	2	2	9	11
Tax effect of prior service costs reclassified from accumulated other comprehensive income (loss)	0	(1)	0	(2)
Tax effect of net actuarial loss reclassified from accumulated other comprehensive income (loss)	(2)	0	(8)	(2)
Talen Energy Supply
Tax effect of available for sale securities arising during the period	24	1	23	(20)
Tax effect of prior service costs for defined benefit plans	0	0	2	0
Tax effect of net actuarial gain for defined benefit plans	0	0	(30)	0
Tax effect of available-for-sale securities reclassified from accumulated other comprehensive income (loss)	0	4	2	6
Tax effect of qualifying derivatives reclassified from accumulated other comprehensive income (loss)	2	2	9	11
Tax effect of prior service costs reclassified from accumulated other comprehensive income (loss)	0	(1)	0	(2)
Tax effect of net actuarial loss reclassified from accumulated other comprehensive income (loss)	$ (2)	$ 0	$ (8)	$ (2)

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash Flows from Operating Activities
Net income (loss)	$ (279)	$ 48
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation	259	242
Amortization	137	117
Defined benefit plans - expense	35	34
Deferred income taxes and investment tax credits	(30)	(150)
Impairment of assets	592	20
Unrealized (gains) losses on derivatives, and other hedging activities	(80)	216
Other	76	19
Change in current assets and current liabilities
Accounts receivable	64	(1)
Accounts payable	(148)	(45)
Unbilled revenues	93	41
Fuel, materials and supplies	58	(67)
Prepayments	23	5
Counterparty collateral	76	(18)
Price risk management assets and liabilities	(9)	(34)
Taxes payable	(23)	70
Other	(32)	(14)
Other operating activities
Defined benefit plans - funding	(74)	(32)
Other assets	1	(2)
Other liabilities	(8)	16
Net cash provided by operating activities	731	465
Cash Flows from Investing Activities
Expenditures for property, plant and equipment	(252)	(276)
Expenditures for intangible assets	(35)	(38)
Purchases of nuclear plant decommissioning trust investments	(154)	(124)
Proceeds from the sale of nuclear plant decommissioning trust investments	143	112
Proceeds from the receipt of grants	0	164
Net (increase) decrease in restricted cash and cash equivalents	110	(199)
Other investing activities	15	17
Net cash provided by (used in) investing activities	(173)	(344)
Cash Flows from Financing Activities
Issuance of long-term debt	600	0
Retirement of long-term debt	(33)	(308)
Contributions from member	82	730
Distributions to member	(214)	(1,178)
Net increase (decrease) in short-term debt	(667)	590
Other financing activities	(30)	0
Net cash provided by (used in) financing activities	(262)	(166)
Net Increase (Decrease) in Cash and Cash Equivalents	296	(45)
Cash and Cash Equivalents at Beginning of Period	352	239
Cash and Cash Equivalents at End of Period	648	194
Talen Energy Supply
Cash Flows from Operating Activities
Net income (loss)	(279)	48
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation	259	242
Amortization	137	117
Defined benefit plans - expense	35	34
Deferred income taxes and investment tax credits	(30)	(150)
Impairment of assets	592	20
Unrealized (gains) losses on derivatives, and other hedging activities	(80)	216
Other	76	19
Change in current assets and current liabilities
Accounts receivable	64	(1)
Accounts payable	(148)	(45)
Unbilled revenues	93	41
Fuel, materials and supplies	58	(67)
Prepayments	23	5
Counterparty collateral	76	(18)
Price risk management assets and liabilities	(9)	(34)
Taxes payable	(23)	70
Other	(32)	(14)
Other operating activities
Defined benefit plans - funding	(74)	(32)
Other assets	1	(2)
Other liabilities	(8)	16
Net cash provided by operating activities	731	465
Cash Flows from Investing Activities
Expenditures for property, plant and equipment	(252)	(276)
Expenditures for intangible assets	(35)	(38)
Purchases of nuclear plant decommissioning trust investments	(154)	(124)
Proceeds from the sale of nuclear plant decommissioning trust investments	143	112
Proceeds from the receipt of grants	0	164
Net (increase) decrease in restricted cash and cash equivalents	110	(199)
Other investing activities	15	17
Net cash provided by (used in) investing activities	(173)	(344)
Cash Flows from Financing Activities
Issuance of long-term debt	600	0
Retirement of long-term debt	(33)	(308)
Contributions from member	82	730
Distributions to member	(215)	(1,178)
Net increase (decrease) in short-term debt	(667)	590
Other financing activities	(29)	0
Net cash provided by (used in) financing activities	(262)	(166)
Net Increase (Decrease) in Cash and Cash Equivalents	296	(45)
Cash and Cash Equivalents at Beginning of Period	352	239
Cash and Cash Equivalents at End of Period	$ 648	$ 194

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents		$ 648	$ 352
Restricted cash and cash equivalents		67	176
Accounts receivable (less reserve:)
Customer		261	186
Other		36	103
Accounts receivable from affiliates		0	36
Unbilled revenues		125	218
Fuel, materials and supplies		468	455
Prepayments		52	70
Deferred income taxes		114	8
Price risk management assets		576	1,079
Assets of discontinued operations		266	0
Other current assets		9	18
Total Current Assets		2,622	2,701
Investments
Nuclear plant decommissioning trust funds		913	950
Other investments		25	30
Total Investments		938	980
Property, Plant and Equipment
Generation		13,167	11,318
Nuclear fuel		652	624
Other		320	293
Less: accumulated depreciation		6,479	6,242
Property, plant and equipment, net		7,660	5,993
Construction work in progress		411	443
Total Property, Plant and Equipment, net		8,071	6,436
Other Noncurrent Assets
Goodwill		0	72
Other intangibles		309	257
Price risk management assets		226	239
Other noncurrent assets		88	75
Total Other Noncurrent Assets		623	643
Total Assets		12,254	10,760
Current Liabilities
Short-term debt		0	630
Long-term debt due within one year		654	535
Accounts payable		278	361
Accounts payable to affiliates		0	50
Taxes		13	28
Interest		68	16
Price risk management liabilities		506	1,024
Liabilities of discontinued operations		5	0
Counterparty collateral		92	16
Other current liabilities		232	230
Total Current Liabilities		1,848	2,890
Long-term Debt		3,376	1,683
Deferred Credits and Other Noncurrent Liabilities
Deferred income taxes		1,559	1,223
Investment tax credits		26	27
Price risk management liabilities		178	193
Accrued pension obligations		253	299
Asset retirement obligations		472	415
Other deferred credits and noncurrent liabilities		140	123
Total Deferred Credits and Other Noncurrent Liabilities		$ 2,628	$ 2,280
Commitments and Contingent Liabilities
Equity
Predecessor Member's Equity	[1]	$ 0	$ 3,930
Common Stock - $0.001 par value	[2]	0	0
Earnings reinvested		4,719	0
Accumulated other comprehensive income (loss)		(311)	0
Total Equity		(6)	(23)
Total Equity		4,402	3,907
Total Liabilities and Equity		12,254	10,760
Talen Energy Supply
Current Assets
Cash and cash equivalents		648	352
Restricted cash and cash equivalents		67	176
Accounts receivable (less reserve:)
Customer		261	186
Other		36	103
Accounts receivable from affiliates		0	36
Unbilled revenues		125	218
Fuel, materials and supplies		468	455
Prepayments		52	70
Deferred income taxes		114	8
Price risk management assets		576	1,079
Assets of discontinued operations		266	0
Other current assets		9	18
Total Current Assets		2,622	2,701
Investments
Nuclear plant decommissioning trust funds		913	950
Other investments		25	30
Total Investments		938	980
Property, Plant and Equipment
Generation		13,167	11,318
Nuclear fuel		652	624
Other		320	293
Less: accumulated depreciation		6,479	6,242
Property, plant and equipment, net		7,660	5,993
Construction work in progress		411	443
Total Property, Plant and Equipment, net		8,071	6,436
Other Noncurrent Assets
Goodwill		0	72
Other intangibles		309	257
Price risk management assets		226	239
Other noncurrent assets		88	75
Total Other Noncurrent Assets		623	643
Total Assets		12,254	10,760
Current Liabilities
Short-term debt		0	630
Long-term debt due within one year		654	535
Accounts payable		278	361
Accounts payable to affiliates		0	50
Taxes		13	28
Interest		68	16
Price risk management liabilities		506	1,024
Liabilities of discontinued operations		5	0
Counterparty collateral		92	16
Other current liabilities		232	230
Total Current Liabilities		1,848	2,890
Long-term Debt		3,376	1,683
Deferred Credits and Other Noncurrent Liabilities
Deferred income taxes		1,559	1,223
Investment tax credits		26	27
Price risk management liabilities		178	193
Accrued pension obligations		253	299
Asset retirement obligations		472	415
Other deferred credits and noncurrent liabilities		140	123
Total Deferred Credits and Other Noncurrent Liabilities		$ 2,628	$ 2,280
Commitments and Contingent Liabilities
Equity
Member's Equity		$ 4,402	$ 3,907
Total Liabilities and Equity		$ 12,254	$ 10,760
[1]	Represents Talen Energy Supply's predecessor member's equity prior to the June 1, 2015 spinoff transaction. Upon completion of the spinoff, the predecessor member's equity was transferred to Talen Energy Corporation's additional paid-in capital. See Note 1 for additional information on the spinoff.
[2]	1,000,000 shares authorized; 128,509 shares issued and outstanding at September 30, 2015.

CONDENSED CONSOLIDATED BALANCE7

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Accounts receivable reserve for uncollectible accounts	$ 1	$ 2
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	1,000,000,000
Common stock, shares issued (in shares)	128,509,000
Common stock, shares outstanding (in shares)	128,509,000
Talen Energy Supply
Accounts receivable reserve for uncollectible accounts	$ 1	$ 2

CONDENSED CONSOLIDATED STATEME8

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Millions		Total		Common Stock		Additional Paid-in Capital	Earnings Reinvested	AOCI		Predecessor Member's Equity		Talen Energy Supply
Beginning balance at Dec. 31, 2013		$ 4,798	[1]					$ 77	[1]	$ 4,721	[1]	$ 4,798
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		48								48	[1]	48
Other comprehensive income (loss)		1						1				1
Distributions to member		(1,212)								(1,212)	[1]	(1,212)
Contributions from member		730								730	[1]	730
Ending balance at Sep. 30, 2014		4,365	[1]					78	[1]	4,287	[1]	4,365
Beginning balance at Dec. 31, 2014												3,907
Beginning balance at Dec. 31, 2014		3,907				$ 0	$ 0	(23)		3,930	[1]
Beginning balance, shares at Dec. 31, 2014	[2]			0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(279)										(279)
Other comprehensive income (loss)		17						17				17
Distributions to member		(396)	[1]							(396)	[1]	(397)
Contributions from member		250	[1]							250	[1]	1,154	[3]
Common stock issued for acquisition of RJS Power		902				902
Common stock issued for acquisition of RJS Power, shares	[2]			44,975
Stock issuance (shares)	[2]			10
Stock issuance expense		(1)				(1)
Stock-based compensation		2				2
Consummation of spinoff transaction	[4]	0				3,816				(3,816)
Consummation of spinoff transaction, shares	[2]			83,524
Ending balance at Sep. 30, 2015												$ 4,402
Ending balance at Sep. 30, 2015		$ 4,402				$ 4,719	$ (311)	$ (6)		$ 0	[1]
Ending balance, shares at Sep. 30, 2015		128,509		128,509	[2]
[1]	Represents Talen Energy Supply's predecessor member's equity balance and activity prior to the June 1, 2015 spinoff transaction.
[2]	Shares in thousands. Each share entitles the holder to one vote on any questions presented at any stockholders' meeting.
[3]	Includes the contribution of RJS Power as of the acquisition date. See Notes 1 and 7 for additional information.
[4]	Upon consummation of the spinoff on June 1, 2015, Talen Energy Supply's predecessor member's equity balance was transferred to Talen Energy Corporation's "Additional paid-in capital." See Note 1 for additional information on the spinoff.

Business and Basis of Presentat

Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Basis of Presentation	Business and Basis of Presentation Capitalized terms and abbreviations appearing in the unaudited combined notes to condensed consolidated financial statements are defined in the glossary. Dollars are in millions, except per share data, unless otherwise noted. Business - Spinoff from PPL and formation of Talen Energy Corporation Talen Energy Corporation, through its principal subsidiary Talen Energy Supply, is a competitive energy and power generation company primarily engaged in the production and sale of electricity, capacity and related products. Talen Energy is headquartered in Allentown, Pennsylvania and owns and operates a portfolio of generation assets principally located in PJM and ERCOT. In June 2014, PPL and Talen Energy Supply executed definitive agreements with the Riverstone Holders to combine their competitive power generation businesses into a new, stand-alone, publicly traded company named Talen Energy Corporation. On June 1, 2015, PPL completed the spinoff to PPL shareowners of a newly formed entity, Talen Energy Holdings, Inc. (Holdco), which at such time owned all of the membership interests of Talen Energy Supply and all of the common stock of Talen Energy Corporation. Immediately following the spinoff, Holdco merged with a special purpose subsidiary of Talen Energy Corporation, with Holdco continuing as the surviving company to the merger and as a wholly owned subsidiary of Talen Energy Corporation and the sole owner of Talen Energy Supply. PPL does not have an ownership interest in Talen Energy Corporation after completion of the spinoff. Substantially contemporaneous with the spinoff and merger, RJS Power was contributed by the Riverstone Holders to become a subsidiary of Talen Energy Supply (referred to as the "combination" or the "acquisition"). Subsequent to the acquisition, RJS Power was merged into Talen Energy Supply. Talen Energy has treated the combination with RJS Power as an acquisition, with Talen Energy Supply considered the accounting acquirer in accordance with business combination accounting guidance. See Note 7 for additional information on the acquisition. See Note 4 for information on Talen Energy Corporation's common shares issued as a result of the formation of Talen Energy Corporation. See Note 6 for information on a syndicated secured credit facility entered into on the spinoff date that replaced Talen Energy Supply's previously outstanding unsecured syndicated credit facility and for the number of shares of preferred stock that Talen Energy Corporation is authorized to issue. Following the announcement of the transaction to form Talen Energy , efforts were initiated to identify the appropriate staffing for Talen Energy following completion of the spinoff. Organizational plans were substantially completed in 2014. The new organizational plans identified the need to resize and restructure the Talen Energy organization and as a result, in 2014, estimated charges for employee separation benefits were recorded. See Talen Energy Supply's Note 4 to the Financial Statements in the 2015 Prospectus for additional information. The separation benefits include cash severance compensation, lump sum COBRA reimbursement payments and outplacement services. Most separations and payment of separation benefits have been completed. The recorded liabilities related to the separation benefits, which are included in "Other current liabilities" on the Balance Sheets, were insignificant at September 30, 2015 and $9 million at December 31, 2014 . In connection with the spinoff transaction, additional employee-related costs were incurred by Talen Energy, which primarily related to accelerated stock-based compensation and pro-rated performance-based cash incentive and stock-based compensation awards previously issued under PPL stock incentive programs, primarily for Talen Energy Supply employees and for PPL employees who became Talen Energy Supply employees in connection with the transaction. These costs were recognized at the closing of the spinoff. During the nine months ended September 30, 2015 , Talen Energy Supply recorded $25 million related to these accelerated stock-based compensation and pro-rated stock-based compensation awards. As the vesting for all Talen Energy Supply employees was accelerated and all remaining unrecognized compensation expense accelerated concurrently with the spinoff, Talen Energy does not expect to recognize future compensation costs for equity awards from PPL stock incentive programs held by Talen Energy Supply employees. See Note 8 for additional information on stock-based compensation. In addition, during the nine months ended September 30, 2015 , Talen Energy incurred $10 million of restructuring costs related to the spinoff transaction, which are recorded in "Operation and maintenance" on the Statement of Income. Prior to completion of the spinoff, Talen Energy Supply's financial statements included certain transactions with affiliates of PPL, which were disclosed as related party transactions. After June 1, 2015, all transactions with PPL or its affiliates are no longer related party transactions. See Note 11 for additional information on related party transactions. Also, prior to the spinoff, the income tax provision for Talen Energy Supply was calculated in accordance with an intercompany tax sharing agreement with PPL, that calculated taxable income as if Talen Energy Supply, and any of PPL's other domestic subsidiaries, each filed a separate return. Tax benefits were not shared between companies. The PPL entity that generated a tax benefit was the entity that was entitled to the tax benefit. Talen Energy has implemented a similar intercompany tax sharing agreement with Talen Energy Corporation filing a consolidated federal income tax return. The effect of Talen Energy Corporation filing a consolidated tax return is taken into account in the settlement of current taxes and the recognition of deferred taxes. Following the spinoff, certain services, including information technology, financial and accounting, human resource and other specified services are provided by PPL on a transition basis pursuant to the TSA. The TSA with PPL is for a period of up to two years from the date of the spinoff. For the three and nine months ended September 30, 2015 , the costs incurred for these services were $9 million and $14 million. See Note 11 for information on the TSA with Topaz Power Management, LP. In connection with the FERC approval of the combination of Talen Energy Supply with RJS Power, PPL, Talen Energy and RJS Power agreed that within twelve months following the closing of the transaction, Talen Energy will enter into an agreement to divest between 1,300 MW and 1,400 MW of assets in one of two groups of assets (both of which include the Sapphire facilities within PJM and the first of which also includes the Holtwood, Lake Wallenpaupack and C.P. Crane facilities and the other of which includes the Ironwood facility) and to limit PJM energy market offers from assets it would retain in the other group to cost-based offers. In September 2015, Talen Energy requested that the FERC approve a third option for complying with the mitigation requirement that consists of Ironwood, Holtwood, Lake Wallenpaupack and C.P. Crane, but excludes the Sapphire facilities. The timing of FERC's response is not known at this time. See Note 7 for information on the anticipated mitigation sales and the classification of Sapphire as discontinued operations. Basis of Presentation Talen Energy Corporation's obligation to report under the Securities and Exchange Act of 1934, as amended, commenced on May 1, 2015, the date Talen Energy Corporation's Registration Statement on Form S-1 relating to the spinoff transaction was declared effective by the SEC. Talen Energy Supply is a separate registrant and is considered the predecessor of Talen Energy Corporation. Therefore, the financial information prior to June 1, 2015 presented in this Quarterly Report on Form 10-Q for both registrants includes only legacy Talen Energy Supply information. From June 1, 2015, upon completion of the spinoff and acquisition, Talen Energy Corporation's and Talen Energy Supply's consolidated financial information also includes RJS. As such, Talen Energy Corporation's and Talen Energy Supply's consolidated financial information presented in this Quarterly Report on Form 10-Q for the 2015 periods represents three and nine months of legacy Talen Energy Supply information consolidated with three and four months of RJS information, while the 2014 periods represent only legacy Talen Energy Supply information. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X and, therefore, do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation in accordance with GAAP are reflected in the condensed consolidated financial statements. All adjustments are of a normal recurring nature, except as otherwise disclosed. The Balance Sheets at December 31, 2014 are derived from Talen Energy Supply's 2014 audited Balance Sheet. The financial statements and notes thereto should be read in conjunction with the financial statements and notes contained in the 2015 Prospectus. The results of operations for the three and nine months ended September 30, 2015 are not necessarily indicative of the results to be expected for the full year ending December 31, 2015 or other future periods, because results for interim periods can be disproportionately influenced by various factors, developments and seasonal variations. The classification of certain prior period amounts has been changed to conform to the presentation in the September 30, 2015 financial statements. "Income (Loss) from Discontinued Operations (net of income taxes)" for the three and nine months ended September 30, 2015 on the Statement of Income represents the activities of Sapphire, the assets and liabilities of which, at September 30, 2015 , have been classified as "Assets of discontinued operations" and "Liabilities of discontinued operations" on the Balance Sheet, except for Sapphire's heat rate call options and working capital items, which may be retained, and therefore were not included in "Liabilities of discontinued operations" on the Balance Sheet. The Sapphire discontinued operations, discussed herein, excludes the heat rate call options. "Income (Loss) from Discontinued Operations (net of income taxes)" for the three and nine months ended September 30, 2014 on the Statement of Income represents the activities of Talen Montana's hydroelectric generating facilities sold in the fourth quarter of 2014 . The Statements of Cash Flows do not separately report the cash flows of discontinued operations. See Note 7 for additional information. Revenue Adjustments During the nine months ended September 30, 2015 , Talen Energy recorded a $7 million decrease to "Retail energy" revenues on the 2015 Statement of Income. Prior to this date, Talen Energy billed and collected amounts from a third party that had a transmission operating agreement with Talen Energy's former affiliate, PPL Electric. Such amounts should have been recognized as an affiliate payable, but were inadvertently recorded as revenue. The $4 million after-tax ( $0.03 per share for Talen Energy Corporation) impact of correcting this overstatement of "Retail energy" revenues decreased "Income (Loss) from Continuing Operations after Income Taxes" and "Net Income (Loss)" during the nine months ended September 30, 2015 . The impact of the overstatement was not material to the previously-issued financial statements and the correction is not expected to be material to the full year results for 2015 . During the three and nine months ended September 30, 2014, Talen Energy recorded $14 million ( $9 million after-tax) and $17 million ( $11 million after-tax) increases to "Energy-related businesses" revenues and "Income (Loss) from Continuing Operations before Income Taxes" on the 2014 Statement of Income related to prior periods and the timing of revenue recognition for a mechanical contracting and engineering subsidiary. The $9 million and $11 million after-tax impact ( $0.11 and $0.13 per share for Talen Energy Corporation) of correcting this error increased "Income (Loss) from Continuing Operations after Income Taxes" and "Net Income (Loss)" in 2014. The impact of the errors is not material to the previously-issued financial statements and was not material to the full year results for 2014.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The following accounting policy disclosures represent updates to Talen Energy Supply's Note 1 to the Financial Statements in the 2015 Prospectus and should be read in conjunction with those disclosures. New Accounting Guidance Adopted Reporting of Discontinued Operations Effective January 1, 2015, Talen Energy prospectively adopted accounting guidance that changes the criteria for determining what should be classified as a discontinued operation and the related presentation and disclosure requirements. A discontinued operation may include a component of an entity or a group of components of an entity, or a business activity. A disposal of a component of an entity or a group of components of an entity is required to be reported in discontinued operations if the disposal represents a strategic shift that has (or will have) a major effect on the entity's operations and financial results when any of the following occurs: (1) the components of an entity or a group of components of an entity meets the criteria to be classified as held for sale, (2) the component of an entity or a group of components of an entity is disposed of by sale, or (3) the component of an entity or a group of components of an entity is disposed of other than by sale (for example, by abandonment or in a distribution to owners in a spinoff). The initial adoption of this guidance did not have a significant impact on Talen Energy but will impact the amounts presented as discontinued operations and will enhance the related disclosure requirements related to future disposals or held for sale classifications. Accounting for Measurement-Period Adjustments Effective September 30, 2015, Talen Energy prospectively adopted accounting guidance that requires an acquirer in a business combination to recognize measurement-period adjustments in the period in which the amounts are determined, including the effect on earnings of any amounts that would have been recorded in prior periods as if the accounting would have been completed at the acquisition date. The acquirer must disclose, by line item, the portion of the adjustment recorded in the current period income statement that would have been recognized in prior periods if the adjustment had been recognized as of the acquisition date. This guidance applies to open measurement periods, and therefore applies to any measurement period adjustments made for the acquisition of RJS Power. See Note 7 for additional information.

Segment and Related Information

Segment and Related Information	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Segment and Related Information	Segment and Related Information Effective June 1, 2015, in connection with the spinoff and acquisition transactions, Talen Energy is organized in two segments: East and West, primarily based on geographic location and energy market characteristics. Prior to the spinoff and acquisition, Talen Energy operated within a single segment. The East segment consists primarily of competitive generation in PJM and wholesale, retail, marketing and trading activities in the eastern U.S. and the legacy Talen Energy Supply coal fired facility, Colstrip, in Montana. As such, the East segment includes all legacy Talen Energy Supply operations and from June 1, 2015, the Raven operations that were acquired from the Riverstone Holders. Although all of the legacy single segment's activity is still included in one segment (East), segment information for periods prior to the spinoff has been revised to reflect the current period presentation as the measurement of segment performance has changed. Previously, net income was used as the measure of segment performance. Beginning in June 2015, operating income and certain non-GAAP measures are used as measures of segment performance. As the Sapphire portfolio is classified as discontinued operations, its results are not included in the East segment's operating income, but the Sapphire portfolio assets are included with the East segment's assets. The West segment consists of the competitive generation and wholesale activities related to the Jade operations that were acquired from the Riverstone Holders on June 1, 2015, which are located in ERCOT. "Other" primarily includes wages, benefits, services, certain insurance, rent and financing costs incurred primarily at Talen Energy Supply, which have not been allocated or assigned to the segments, and is presented to reconcile segment information to consolidated results. Financial data for the segments and reconciliation to consolidated results for the periods ended September 30 are: Three Months Nine Months 2015 2014 2015 2014 Income Statement Data Revenues from external customers (a) East $ 1,325 $ 1,601 $ 3,305 $ 1,653 West 94 — 125 — Total $ 1,419 $ 1,601 $ 3,430 $ 1,653 Operating Income (Loss) East $ (230 ) $ 242 $ 132 $ 307 West 24 — 18 — Other (40 ) (53 ) (184 ) (181 ) Total $ (246 ) $ 189 $ (34 ) $ 126 Balance Sheet Data September 30, 2015 December 31, 2014 Assets East $ 11,128 $ 10,468 West 1,066 — Other (b) 60 292 Total Assets $ 12,254 $ 10,760 (a) Includes unrealized gains and losses from derivatives. See Note 14 for additional information. (b) Primarily consists of unallocated items, including cash and PP&E.

Earnings (Loss) Per Share for T

Earnings (Loss) Per Share for Talen Energy Corporation	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Earnings (Loss) Per Share for Talen Energy Corporation	Earnings (Loss) Per Share for Talen Energy Corporation On June 1, 2015, the spinoff date, Talen Energy Corporation issued 128,499,023 shares of common stock, including 83,524,365 shares issued to PPL's shareholders and 44,974,658 shares issued in a private placement to the Riverstone Holders. To calculate basic and diluted EPS for periods presented prior to June 1, 2015, Talen Energy Corporation used the shares issued to PPL's shareholders on the date of the spinoff as Talen Energy Corporation was a wholly owned subsidiary of PPL and no shares were outstanding prior to that date. The calculation of basic and diluted earnings per share for the three and nine months ended September 30, 2015 utilized the weighted-average shares outstanding during this period assuming the shares issued to PPL's shareholders were outstanding during the entire period and reflects the impact of the private placement of shares to the Riverstone Holders on the spinoff date. Basic EPS is computed by dividing income by the weighted-average number of common shares outstanding during the applicable period. Diluted EPS is computed by dividing income by the weighted-average number of common shares outstanding, increased by incremental shares that would be outstanding if potentially dilutive non-participating securities were converted to common shares as calculated using the Treasury Stock Method. Reconciliations of the amounts of income and shares of Talen Energy Corporation common stock (in thousands) for the periods ended September 30 used in the EPS calculation are: Three Months Nine Months 2015 2014 2015 2014 Income (Numerator) Income (Loss) from continuing operations after income taxes $ (339 ) $ 94 $ (218 ) $ 38 Income (Loss) from discontinued operations (net of income taxes) (62 ) 7 (61 ) 10 Net Income (Loss) $ (401 ) $ 101 $ (279 ) $ 48 Shares of Common Stock (Denominator) Weighted-average shares - Basic EPS 128,509 83,524 103,627 83,524 Weighted-average shares - Diluted EPS 128,509 83,524 103,627 83,524 Share-based payment awards of 1,263 thousand and 525 thousand were excluded from the computations of diluted EPS for the three and nine months ended September 30, 2015 because the effect would have been antidilutive.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Selected information regarding Talen Energy's income tax provision for the periods ended September 30 was as follows: Three Months Nine Months 2015 2014 2015 2014 Income (Loss) from Continuing Operations Before Income Taxes $ (300 ) $ 168 $ (169 ) $ 54 Income Taxes $ 39 $ 74 $ 49 $ 16 Effective Tax Rate (13 )% 44 % (29 )% 30 % Talen Energy recorded taxes during the nine month period at an interim period annualized effective tax rate of 30.76% in 2015 compared with 36.93% in 2014 . However, Talen Energy's income tax expense reflected in the table above does not bear a customary relationship to income (loss) from continuing operations before income taxes primarily as a result of the impact of the recognition of an impairment of non-deductible goodwill, uncertain tax benefits, state deferred rate changes, tax return adjustments, tax credits and the impact of state and local income taxes. In February 2015, PPL and the IRS Appeals division reached a tentative settlement on PPL's open audits for the years 1998 - 2011. The settlement was required to be reviewed and approved by the Joint Committee on Taxation (JCT) before considered final. In April 2015, PPL was notified that the JCT approved PPL's settlement. During the nine months ended September 30, 2015 , Talen Energy recorded a tax benefit of $12 million for its portion of the settlement of previously unrecognized tax benefits. Also in 2015, Talen Energy recorded a tax benefit of $17 million during the nine months ended September 30, related to its state deferred tax liabilities for changes in state apportionment and the impact on the future estimated state income tax rate as a result of the acquisition of RJS Power.

Financing Activities

Financing Activities	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Financing Activities	Financing Activities Credit Arrangements and Short-term Debt Talen Energy maintains credit facilities to enhance liquidity and provide credit support. The amounts borrowed below are recorded as "Short-term debt" on the Balance Sheets. The following credit facility was in place at: September 30, 2015 Expiration Date Capacity Borrowed Letters of Unused Capacity Syndicated Secured Credit Facility (a) June 2020 $ 1,850 $ — $ 334 $ 1,516 (a) The facility includes capacity available for letters of credit and for short-term borrowings. The facility requires Talen Energy Supply to maintain a senior secured debt to adjusted EBITDA ratio (as defined in the agreement) of less than or equal to 4.50 to 1.00 as of the last day of any fiscal quarter. The company pays customary fees on the facility and borrowings bear interest at the company's option at either a defined base rate or LIBOR-based rates, in each case plus an applicable margin. The syndicated secured credit facility was entered into on June 1, 2015 in connection with the completion of the spinoff transaction and replaced Talen Energy Supply's previously existing unsecured syndicated credit facility. Talen Energy Supply is the borrower under the new facility. Any outstanding principal amounts under the old facility were repaid prior to the termination of the old facility and outstanding letters of credit were transferred to the new facility. The facility is secured by liens on the assets of Talen Energy Supply and is guaranteed by certain Talen Energy Supply subsidiaries, which guarantees are in turn secured by liens on assets of such subsidiaries with an aggregate carrying value of $7 billion at September 30, 2015. The facility provides the option to raise incremental credit facilities, refinance the loans with debt incurred outside the facility and extend the maturity date of the revolving credit commitments and loans and, if applicable, term loans, subject to certain limitations. In October 2015, Talen Energy Supply borrowed $400 million under this facility to finance a portion of the MACH Gen, LLC acquisition. As of October 31, 2015, the total amount outstanding under the facility was $550 million (excluding letters of credit), with a weighted average interest rate of 2.44% . The Talen Energy Supply letter of credit facility and uncommitted credit facilities that existed at December 31, 2014 either expired or matured during the first quarter of 2015. Any previously issued letters of credit under these facilities were either terminated or reissued under the then-outstanding unsecured syndicated credit facility, and upon closing of the spinoff were reissued under the new syndicated secured credit facility described above. During the nine months ended September 30, 2015 , Talen Energy wrote-off $12 million of unamortized fees to "Interest expense" on the Statements of Income as a result of the termination of the prior credit facility. Talen Energy Supply maintains a $500 million agreement expiring June 2017 that provides Talen Energy Supply the ability to request up to $500 million of committed unsecured letter of credit capacity at fees to be agreed upon at the time of each request, based on certain market conditions. At September 30, 2015 , Talen Energy Supply had not requested any capacity for the issuance of letters of credit under this agreement. Talen Energy Supply and its subsidiaries, Talen Energy Marketing, Montour, LLC and Brunner Island, LLC maintain an $800 million energy marketing and trading facility, whereby Talen Energy Marketing receives credit to be applied to satisfy collateral posting obligations related to its energy marketing and trading activities with counterparties participating in the facility. Certain of Talen Energy Marketing's obligations under the facility are guaranteed by Talen Energy Supply. Additionally, prior to the spinoff transaction, Montour, LLC and Brunner Island, LLC had guaranteed certain of Talen Energy Marketing's obligations and had granted mortgage liens on their respective generating facilities to secure such guarantees. In connection with the spinoff from PPL, the guarantees and liens by Montour, LLC and Brunner Island, LLC were released and Talen Energy Supply agreed to provide facility counterparties with substitute collateral in the form of cash or letters of credit. The facility is for a five -year term that is subject to an automatic extension each year under certain circumstances. The current term as so extended expires in November 2019 . Long Term Debt In May 2015, Talen Energy Supply issued $600 million of 6.50% Senior Unsecured Notes due 2025 . Talen Energy Supply received proceeds of $591 million , net of underwriting fees, which were used for repayment of short-term debt. The notes may be redeemed at Talen Energy Supply's option, in whole at any time or in part from time to time, prior to June 1, 2020 at a price equal to 100% of their principal amount plus a make-whole premium and on or after June 1, 2020 at specified redemption prices. In addition, on or prior to June 1, 2018, up to 35% of the notes may be redeemed by Talen Energy Supply with proceeds from certain equity offerings at a price equal to 106.5% of the principal amount. In June 2015, Talen Energy Supply assumed $1.25 billion of RJS Power Holdings LLC's 5.125% Senior Notes due 2019 as a result of the merger of RJS Power Holdings LLC into Talen Energy Supply, by which Talen Energy Supply became the obligor of these notes. In connection with this event and pursuant to the terms of the indenture governing the notes, the coupon on the notes was reduced to 4.625% in July 2015. In September 2015, Talen Energy Supply completed a remarketing of $231 million of Exempt Facilities Revenue Refunding Bonds, Series 2009A due 2038, Series 2009B due 2038, and Series 2009C due 2037 that were issued by PEDFA on behalf of Talen Energy Supply in 2009. All series bore interest at a fixed rate of 3.0% prior to the remarketing. The Series 2009A Bonds, with a principal amount of $100 million , were remarketed at a fixed coupon of 6.40% to maturity. The Series 2009B Bonds and Series 2009C Bonds, with an aggregate principal amount of $131 million , were remarketed at a fixed rate of 5.00% for five years, at which time they will be subject to mandatory repurchase and optional remarketing. This transaction is excluded from the Statement of Cash Flows as a non-cash transaction. In October 2015, Talen Energy Supply's $300 million of 5.70% REset Put Securities due 2035 (REPS) were subject to mandatory tender to the remarketing dealer. However, the remarketing dealer and Talen Energy Supply mutually agreed to terminate the remarketing dealer's right to remarket the REPS and, in accordance with the terms of the REPS, Talen Energy Supply repurchased the REPS at par. The total aggregate consideration paid to repurchase the REPS was $434 million , which included $300 million of principal and $134 million of remarketing option value paid to the remarketing dealer. The termination payment to the remarketing dealer will be recorded to earnings in the fourth quarter of 2015. MACH Gen, LLC Debt Following the MACH Gen, LLC acquisition in November 2015, $578 million of debt under the First Lien Credit and Guaranty Agreement (New MACH Gen Agreement) of New MACH Gen, LLC (a subsidiary of MACH Gen, LLC) remains outstanding, which is comprised of approximately $475 million outstanding under a Term Loan B facility that matures July 2022 and approximately $103 million drawn under a $160 million revolving credit facility that matures July 2021. Obligations under the New MACH Gen Agreement are guaranteed by each of New MACH Gen, LLC's subsidiaries and are secured by a first priority security interest, subject to possible shared first lien status with certain permitted hedge and power sale agreements, in all of the assets of New MACH Gen, LLC and each guarantor, including the equity interests in New MACH Gen, LLC and each guarantor. The weighted average interest rates on the outstanding Term Loan B and revolving credit facility borrowings are 6.21% and 4.98% , respectively. The Term Loan B provides customary annual amortization paid quarterly and may also be repaid, in whole or in part, beginning in the third quarter of 2016 without any make-whole premium. Preferred Stock of Talen Energy Corporation Talen Energy Corporation is authorized under its Amended and Restated Certificate of Incorporation to issue up to 100 million shares of preferred stock. No shares of preferred stock were issued or outstanding at September 30, 2015 .

Acquisitions, Development and D

Acquisitions, Development and Divestitures	9 Months Ended
	Sep. 30, 2015
Acquisitions Development And Divestitures [Abstract]
Acquisitions, Development and Divestitures	Acquisitions, Development and Divestitures Talen Energy from time to time evaluates opportunities for potential acquisitions, divestitures and development projects. Development projects are periodically reexamined based on market conditions and other factors to determine whether to proceed with the projects, sell, cancel or expand them, execute tolling agreements or pursue other options. Any resulting transactions may impact future financial results. See Talen Energy Supply's Note 4 to the Financial Statements in the 2015 Prospectus for additional information. Acquisitions MACH Gen, LLC On November 2, 2015, Talen Energy completed the acquisition of the membership interests of MACH Gen, LLC for $603 million in cash consideration (including estimated working capital). The cash purchase price is subject to post-closing adjustment based on the amounts by which the actual figures vary from the estimates provided at the closing. The purchase price was funded by a borrowing under Talen Energy Supply's syndicated secured credit facility and cash on hand. The Term Loan B and revolving credit facility of New MACH Gen, LLC (a subsidiary of MACH Gen, LLC) remain outstanding following the completion of the transaction. See Note 6 for additional information. MACH Gen, LLC's total generating capacity is approximately 2,500 MW . Talen Energy will apply acquisition accounting to the assets and liabilities of MACH Gen, LLC and its subsidiaries, whereby the purchase price will be allocated to the underlying tangible and intangible assets and liabilities based on their respective fair values on the acquisition date, with the remainder allocated to goodwill. Based on the timing of the acquisition closing date to the filing date of the financial statements, the preliminary purchase price allocation of the assets and liabilities of MACH Gen, LLC are in process and purchase accounting disclosures are not available at the time of the filing of these financial statements. RJS Power On June 1, 2015, substantially contemporaneous with the spinoff by PPL to form Talen Energy, RJS Power was contributed by the Riverstone Holders to become a subsidiary of Talen Energy Supply in exchange for 44,974,658 shares of Talen Energy Corporation common stock. See Notes 1 and 4 for additional information on the spinoff and acquisition. In accordance with business combination accounting guidance, Talen Energy treated the combination with RJS Power as an acquisition and Talen Energy Supply is considered the acquirer of RJS Power. Accordingly, Talen Energy applied acquisition accounting to the assets acquired and liabilities assumed of RJS Power whereby the purchase price was allocated to the underlying tangible and intangible assets acquired and liabilities assumed based on their respective fair values as of June 1, 2015, with the remainder allocated to goodwill. The total consideration for the acquisition was deemed to be $902 million based on the fair value of the Talen Energy Corporation common stock issued for the acquisition using the June 1, 2015 closing "when-issued" market price. The following table summarizes the preliminary allocation of the purchase price to the fair values of the major classes of assets and liabilities of RJS, all of which represent non-cash activity excluded from the Statement of Cash Flows for the nine months ended September 30, 2015 . Current assets (a) $ 164 Assets of discontinued operations (b) 375 PP&E 1,777 Other intangibles (c) 46 Current liabilities (259 ) Liabilities of discontinued operations (5 ) Long-term debt (1,244 ) Deferred income taxes (266 ) Other noncurrent liabilities (d) (80 ) Net identifiable assets acquired 508 Goodwill (e) 394 Net assets acquired $ 902 (a) Includes gross contractual amount of the accounts receivable acquired of $41 million , which approximates fair value. (b) See Note 13 for information on impairment charges recorded during the third quarter of 2015 related to the Sapphire portfolio. (c) Includes $28 million for a pipeline lease that will be amortized over a 14 year period, and $17 million for an ash site permit that has an amortization period of 10 years. (d) Includes $33 million for "out-of-the-money" coal contracts that will be amortized over the contract term as the coal is consumed. (e) The preliminary allocation above is as of the acquisition date of June 1, 2015. As further discussed in Note 15, goodwill was fully impaired at September 30, 2015, which included the goodwill recognized in the acquisition of RJS Power. The purchase price allocation is considered by Talen Energy's management to be provisional and could change materially in subsequent periods. Any changes to the provisional purchase price allocation during the measurement period will be adjusted prospectively. The measurement period can extend up to a year from the date of acquisition, but Talen Energy expects to complete the purchase price allocation by the end of 2015. The items pending finalization include, but are not limited to, the valuation of certain liabilities, goodwill and deferred income taxes. During the third quarter of 2015, certain immaterial purchase accounting reclassification adjustments were made affecting deferred income taxes, assets and liabilities of discontinued operations and current assets and liabilities. Additionally, minor purchase accounting valuation adjustments were made affecting certain current assets and liabilities, PP&E, other intangibles and related deferred income taxes resulting in a $4 million reduction in provisional goodwill. The statement of income effect of these adjustments recorded during the third quarter was insignificant. Goodwill recorded as a result of the acquisition primarily reflected synergies expected to be achieved related to the spinoff and acquisition. The goodwill is not deductible for income tax purposes and has been assigned to the East segment. See Note 15 for additional information related to goodwill. Actual operating revenues and net income of RJS, since the June 1 acquisition, included in Talen Energy's results for the periods ended September 30, 2015 were: Three Months Nine Months Operating Revenues Net Income (Loss) (a) Operating Revenues Net Income (Loss)(a) RJS actual for 2015 $ 237 $ 34 $ 339 $ 48 (a) Includes the operating results of the Sapphire portfolio, which is classified as discontinued operations. Excludes the impact of goodwill and long-lived asset impairments recorded during the three and nine months ended September 30, 2015. See Notes 13 and 15 for information on the impairments recorded. Pro forma information for Talen Energy for the periods ended September 30, as if the acquisition had occurred January 1, 2014, is as follows: Three Months Nine Months Operating Revenues Income (Loss) from Continuing Operations After Tax Operating Revenues Income (Loss) from Continuing Operations After Tax 2015: Pro forma $ 1,420 $ 110 $ 3,723 $ 235 Basic and diluted earnings per share (for Talen Energy Corporation) 0.86 1.83 2014: Pro forma 1,758 79 2,361 47 Basic and diluted earnings per share (for Talen Energy Corporation) 0.61 0.37 The unaudited pro forma financial information has been presented for illustrative purposes only and is not necessarily indicative of results of operations that would have been achieved had the acquisition taken place on the date indicated, or the future consolidated results of operations of Talen Energy. The pro forma financial information presented above has been derived from the historical condensed consolidated financial statements of Talen Energy and from the historical consolidated and combined financial statements of RJS Power. The pro forma financial information presented above includes adjustments for (1) classifying Sapphire as discontinued operations (see Note 1 and "Discontinued Operations - Sapphire" below for additional information), (2) alignment of accounting policies, (3) incremental depreciation and amortization expense related to fair value adjustments to PP&E and identifiable intangible assets and liabilities, (4) incremental interest expense for outstanding borrowings to reflect the terms of the new syndicated credit facility, (5) nonrecurring items (discussed below), (6) the tax effect of the above adjustments, and (7) the issuance of Talen Energy Corporation common stock in connection with the spinoff from PPL and the acquisition of RJS Power. The pro forma financial information presented excludes the impact of impairments recorded during the three and nine months ended September 30, 2015. See Notes 13 and 15 for information on the impairments recorded. Nonrecurring acquisition, integration and other costs directly related to the acquisition during the nine months ended September 30, 2015 of $6 million are recorded in "Operation and maintenance" on the Statements of Income. Adjustments were made in the calculation of pro forma amounts to remove the effect of these nonrecurring items and related income taxes. The pro forma financial information does not include adjustments for potential future cost savings. Anticipated Divestitures Ironwood, Holtwood, Lake Wallenpaupack and C.P. Crane Power Plants In October 2015, Holtwood, LLC, a wholly owned, indirect subsidiary of Talen Energy, entered into an agreement to sell the Holtwood and Lake Wallenpaupack hydroelectric projects in Pennsylvania for a purchase price of $860 million , subject to customary purchase price adjustments. The projects have a combined summer rating operating capacity of 308 MW . The transaction is expected to close in the first quarter of 2016, subject to customary closing conditions and the receipt of required regulatory approvals. In October 2015, Talen Generation entered into an agreement to sell Talen Ironwood Holdings, LLC, which through its subsidiaries owns and operates the Ironwood natural gas combined-cycle plant in Pennsylvania for a purchase price of $654 million , subject to customary purchase price adjustments. In connection with the sale, Talen Energy expects to repay $41 million of indebtedness, plus a customary debt make-whole premium. The Ironwood unit has a summer rating operating capacity of 660 MW . The transaction is expected to close in the first quarter of 2016, subject to customary closing conditions and the receipt of required regulatory approvals. In October 2015, Raven Power Marketing LLC, a wholly owned, indirect subsidiary of Talen Energy, entered into an agreement to sell C.P. Crane LLC, which owns and operates the C.P. Crane coal-fired power plant in Maryland. The C.P. Crane plant has a summer rating operating capacity of 402 MW . The transaction is expected to close in the first quarter of 2016, subject to customary closing conditions and the receipt of required regulatory approvals. The transaction is not expected to have a significant impact on Talen Energy's financial condition or results of operations. See Notes 13 and 15 for information on an impairment recorded during the third quarter of 2015 for this plant. The sales are part of the requirement to divest certain PJM assets to comply with a December 2014 FERC order approving the combination with RJS Power. Discontinued Operations Sapphire As described in Note 1, as part of the FERC approval of the combination with RJS Power as part of the spinoff transaction, certain assets are required to be disposed of under a mitigation plan. Under GAAP, assets acquired through a business combination that are immediately held for sale should be classified as a discontinued operation from the date of acquisition. The Sapphire portfolio is included in both of the divestiture packages currently approved by FERC to satisfy the mitigation requirements of the FERC order approving the combination with RJS Power and therefore meets the criteria for classification as assets and liabilities of discontinued operations on the Balance Sheet and as discontinued operations on the Statements of Income. See Note 1 to the Financial Statements for more information regarding the mitigation options as well as the Sapphire liabilities not included in liabilities of discontinued operations. The assets and liabilities of discontinued operations on the Balance Sheet as of September 30, 2015 consisted of PP&E and an ARO. Following are the components of discontinued operations, since the June 1 acquisition, on the Statement of Income for the periods ended September 30, 2015 . Three Months Nine Months Operating revenues $ 36 $ 44 Operating expenses 27 34 Impairment (a) 109 109 Income (loss) before income taxes (100 ) (99 ) Income tax expense 38 38 Income (Loss) from Discontinued Operations (net of income taxes) $ (62 ) $ (61 ) (a) See Notes 13 and 15 for additional information on this non-cash charge. Talen Montana Hydro Sale In November 2014, Talen Montana completed the sale to NorthWestern Corporation of 633 MW of hydroelectric generating facilities located in Montana for approximately $900 million in cash. The sale included 11 hydroelectric power facilities and related assets. Following are the components of discontinued operations on the Statement of Income for the periods ended September 30 , 2014 . Three Months Nine Months Operating revenues $ 33 $ 103 Interest expense (a) 2 6 Income (loss) before income taxes (b) 11 20 Income (Loss) from Discontinued Operations (net of income taxes) (b) 7 10 (a) Represents allocated interest expense based upon the discontinued operations share of the net assets of Talen Energy. (b) Includes an impairment charge related to the Kerr Dam Project. See Note 13 for additional information on this non-cash charge.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation Talen Energy Corporation grants share-based compensation to eligible participants under the Talen Energy stock incentive plan (SIP). Under the SIP, restricted shares of Talen Energy Corporation stock, restricted stock units, performance units, stock options and stock appreciation rights may be granted to officers and other key employees. Awards under the plan are made by the Compensation, Governance and Nominating Committee (CGNC) of the Talen Energy Corporation Board of Directors. The total number of shares which may be issued under the plan is 5,630,000 and the maximum number of shares for which stock options may be granted is 2,000,000 . Shares delivered under the SIP may be in the form of authorized and unissued Talen Energy Corporation common stock or common stock held in treasury by Talen Energy Corporation. Restricted Stock Units Restricted stock units are awards based on the fair value of Talen Energy Corp oration common stock on the date of grant. Actual Talen Energy Corporation common shares will be issued upon completion of a vesting period, generally three years. Substantially all restricted stock unit awards are expected to vest. The fair value of restricted stock units granted is recognized as compensation expense on a straight-line basis over the service period or through the date the employee reaches retirement eligibility. The fair value of restricted stock units granted to retirement-eligible employees is recognized as compensation expense immediately upon the date of grant. Restricted stock units are subject to forfeiture or accelerated payout under the SIP provisions for termination, retirement, disability and death of employees. Restricted stock units vest fully, in certain situations, as defined by the SIP. The total restricted stock units granted through September 30, 2015 was 261,877 and the grant date fair value per share was $18.86 . Stock Options Stock options have been granted with an option exercise price per share not less than the fair value of Talen Energy Corporation's common stock on the date of grant. Options become exercisable in equal installments over a three -year service period beginning one year after the date of grant, assuming the individual is still employed by Talen Energy or a subsidiary. The CGNC has discretion to accelerate the exercisability of the options. All options expire no later than ten years from the grant date. The options become exercisable immediately in certain situations, as defined by the SIP. The fair value of options granted is recognized as compensation expense on a straight-line basis over the service period or through the date the employee reaches retirement eligibility. Substantially all stock option awards are expected to vest. The fair value of options granted to retirement-eligible employees is recognized as compensation expense immediately upon the date of grant. Stock options granted through September 30, 2015 were 991,101 and the grant date fair value per share was $4.91 . The fair value of each option granted is estimated using a Black-Scholes option-pricing model. Talen Energy uses a risk-free interest rate, expected option life and expected volatility to value its stock options. The risk-free interest rate reflects the yield for a U.S. Treasury Strip available on the date of grant with constant rate maturity approximating the option's expected life. Expected life was calculated using the simplified method described in SEC Staff Accounting Bulletin (SAB) 107/110 (updated by SAB 110). Expected volatility is derived from the volatility of a peer group selected by management as Talen Energy Corporation's common stock does not have a trading history. The assumptions used in the model were: Risk-free interest rate 2.05 % Expected option life 6 years Expected stock volatility 21.55 % Performance Units Performance units represent a target number of shares of Talen Energy Corporation's common stock that the recipient would receive upon Talen Energy Corporation's attainment of an applicable performance goal. For awards granted in 2015, Talen Energy Corporation uses total shareowner return (TSR) which is determined based on total shareowner return during a three -year performance period. At the end of the performance period, payout is determined by comparing Talen Energy Corporation's TSR to the TSR of peer group companies that Talen Energy Corporation has selected. Awards are payable on a graduated basis based on thresholds that measure Talen Energy Corporation's performance relative to the peer group companies on which each years' awards are measured. Awards can be paid up to 200% of the target award or forfeited with no payout if performance is below a minimum established performance threshold. Under the plan provisions, performance units are subject to forfeiture upon termination of employment except for retirement, disability or death of an employee, in which case the total performance units remain outstanding and are eligible for vesting through the conclusion of the performance period. The fair value of performance units is recognized as compensation expense on a straight-line basis over the three -year performance period. Performance units vest on a pro rata basis, in certain situations, as defined by the plan. The fair value of performance units granted was estimated using a Monte Carlo pricing model that values market based performance conditions such as TSR. The model assumed an expected stock volatility of 31.8% that was based on the historical volatility based on daily stock price changes of peer group companies. Performance Units granted through September 30, 2015 were 158,900 and the weighted-average grant date fair value was $21.17 per share. Compensation Expense Prior to the spinoff, restricted shares of PPL common stock, restricted stock units, performance units and stock options were granted to officers and other key employees of Talen Energy. At December 31, 2014 , these employees of Talen Energy had 1,457,900 of unvested shares of restricted stock and restricted stock units, 291,492 of performance units and 2,745,016 of outstanding stock options. These awards and restricted stock and stock options granted to these employees in 2015 prior to the spinoff by PPL, were accelerated for vesting purposes. See Note 1 for information on the recording of expense related to this acceleration. For the nine months ended September 30, 2015 , compensation expense for these awards, excluding the acceleration, but including an allocation of PPL Services' compensation expense for similar awards, was $18 million . The nine months ended September 30, 2015 includes compensation expense of $3 million for Talen Energy Corporation restricted stock units, performance units and stock options accounted for as equity awards. See Note 1 for additional information on the spinoff from PPL.

Defined Benefits

Defined Benefits	9 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Defined Benefits	Defined Benefits Prior to the June 1, 2015 spinoff, the majority of Talen Energy Supply's employees were eligible for pension benefits under a PPL non-contributory defined benefit pension plan, with benefits based on length of service and either career average pay or final average pay, as defined by the plan. Prior to the June 1, 2015 spinoff, this plan was closed to all newly hired employees. Newly hired employees were eligible to participate in a PPL 401(k) savings plan with enhanced employer contributions. Talen Energy was allocated costs of the PPL pension plan based on its employees' participation in the plan. Employees who participated in this PPL pension plan who became employees of Talen Energy Supply transferred into a newly created pension plan sponsored by Talen Energy Supply, which provides benefits similar to that of the PPL pension plan. Prior to the spinoff, the majority of Talen Energy Supply's employees also were eligible for certain health care and life insurance benefits upon retirement through the PPL other postretirement benefit plans, which, prior to the June 1, 2015 spinoff, were closed to all newly hired employees. Talen Energy Supply was allocated costs of the PPL plans based on its employees' participation in the plans. Employees who participated in the health care and life insurance plans and who became employees of Talen Energy Supply transferred into the newly created Talen Energy other postretirement benefit plans sponsored by Talen Energy Supply, which provide benefits similar to those of the PPL other postretirement benefit plans. A remeasurement of the assets and the obligations for the PPL pension and other postretirement benefit plans was performed as of May 31, 2015 in order to separate the assets and obligations of the PPL plans attributable to Talen Energy, as required by the spinoff agreements. The Talen Energy pension plan assumed from PPL the pension benefit obligations for active plan participants who became employees of Talen Energy in connection with the spinoff and for individuals who terminated employment from Talen Energy Supply on or after July 1, 2000. A portion of the PPL pension plan assets were also allocated to the new Talen Energy pension plan. The asset allocation was based on the rules prescribed by ERISA for allocating assets in connection with a pension plan spinoff. The Talen Energy other postretirement benefit plans assumed the other postretirement benefit obligations from PPL for active plan participants who became employees of Talen Energy in connection with the spinoff. PPL retained obligations attributable to existing retirees as of the date of the spinoff. A portion of the PPL other postretirement benefit plan assets, which are held in VEBA trusts and a 401(h) account, were also allocated to the new Talen Energy other postretirement benefit plans. The asset allocation was determined separately for each funding vehicle based on the ratio of the accumulated postretirement benefit obligation (APBO) assumed by Talen Energy to the total APBO attributed to each funding vehicle. As a result of the above, the net funded status of the new Talen Energy pension and other postretirement benefit plans at June 1, 2015 was a liability of $235 million . A portion of the assets allocated to Talen Energy for both the pension and other postretirement benefit plans were transferred to the Talen Energy plans on July 1, 2015 in accordance with the spinoff agreements. The remaining asset transfer is expected to occur by the end of 2015. There were no changes to the pension and other postretirement benefit plans for employees of Talen Montana as a result of the spinoff transaction. However, PPL retained the liability for other postretirement benefits attributable to existing retirees of Talen Montana as of the date of the spinoff. The following table provides the components of net periodic defined benefit costs for Talen Energy pension plans for the periods ended September 30 , for which the nine months of 2015 includes four months of costs under the newly formed Talen Energy pension plan. The net periodic defined benefit costs for other postretirement benefit plans for the periods ended September 30, 2015 and 2014 were insignificant. Pension Benefits Three Months Nine Months 2015 2014 2015 2014 Service cost $ 12 $ 1 $ 19 $ 4 Interest cost 18 3 28 7 Expected return on plan assets (23 ) (3 ) (37 ) (8 ) Amortization of: Actuarial (gain) loss 6 — 9 1 Net periodic defined benefit costs (credits) $ 13 $ 1 $ 19 $ 4 The table below provides the costs from defined benefit plans sponsored by PPL Services allocated to Talen Energy Supply based on its participation in those plans prior to the separation on June 1, 2015, which management believes were reasonable at the time. The allocations include costs related to supplemental retirement benefits for executives and other key management employees through unfunded nonqualified retirement plans. The liabilities for these plans were retained by PPL as of the date of the spinoff. Three Months Nine Months 2015 2014 2015 2014 Pension and other postretirement benefits (a) $ — $ 2 $ 18 $ 32 (a) The three and nine months ended September 30, 2014 includes $(5) million and $11 million of termination benefits (credits) related to a one-time voluntary retirement window offered to certain bargaining unit employees upon the ratification of a new union agreement in June 2014. The benefits offered were consistent with the standard separation program benefits for bargaining unit employees. During the nine months ended September 30, 2014 , $6 million of severance compensation was recorded by Talen Energy related to the 2014 union agreement as mentioned in note (a) above.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Energy Purchase Commitments Talen Energy enters into long-term purchase contracts to supply the coal requirements for its coal-fired generating facilities. These contracts include commitments to purchase coal through 2019. As a result of low market prices and demand for electricity and natural gas, coal utilization has decreased. To mitigate the risk of oversupply, Talen Energy incurred pre-tax charges of $41 million during the three and nine months ended September 30, 2015 to reduce its contracted coal deliveries in 2015 through 2018. These charges were recorded to "Fuel" on the Statement of Income. Legal Matters Talen Energy is involved in legal proceedings, claims and litigation in the ordinary course of business, including, but not limited to, the matters identified below. Talen Energy believes that it has meritorious defenses in connection with its current legal proceedings, claims and litigation, and it intends to vigorously contest each of them. However, there can be no assurance that it will be successful in its efforts. No estimate of the possible loss or range of loss in excess of amounts accrued, if any, can be made at this time regarding any of the matters specifically described below because the inherently unpredictable nature of legal proceedings may be exacerbated by various factors such as ongoing discovery, significant facts that are in dispute, the stage of the proceeding and the wide range of potential outcomes for any such matter. Other than as described below, in the opinion of management based upon information currently available to Talen Energy, while the outcome of these legal proceedings, claims and litigation is uncertain, the likely results of these legal proceedings, claims and litigation are not expected, either individually or in the aggregate, to have a material adverse effect on Talen Energy's financial condition or results of operations, although the effect could be material to Talen Energy's results of operations in any interim reporting period. Sierra Club Litigation In March 2013, the Sierra Club and MEIC filed a complaint in the U.S. District Court, District of Montana, Billings Division against Talen Montana and the other Colstrip Steam Electric Station (Colstrip) owners: Avista Corporation, Puget Sound Energy, Portland General Electric Company, NorthWestern Corporation and PacifiCorp. Talen Montana operates Colstrip on behalf of the owners. The complaint alleged certain violations of the Clean Air Act, including New Source Review, Title V and opacity requirements and listed 39 separate claims for relief. The complaint requested injunctive relief and civil penalties on average of $36,000 per day per violation, including a request that the owners remediate environmental damage and that $100,000 of the civil penalties be used for beneficial mitigation projects. In July 2013, the Sierra Club and MEIC filed an additional Notice of Intent to Sue, identifying additional plant projects that are alleged not to be in compliance with the Clean Air Act and, in September 2013, filed an amended complaint. The amended complaint dropped all claims regarding pre-2001 plant projects, as well as the plaintiffs' Title V and opacity claims. It did, however, add claims with respect to a number of post-2000 plant projects, which effectively increased the number of projects subject to the litigation by about 40 . Talen Montana and the other Colstrip owners filed a motion to dismiss the amended complaint in October 2013. In May 2014, the court dismissed the plaintiffs' independent Best Available Control Technology claims and their Prevention of Significant Deterioration (PSD) claims for three projects, but denied the owners' motion to dismiss the plaintiffs' other PSD claims on statute of limitation grounds. In August 2014, the Sierra Club and MEIC filed a second amended complaint. This complaint includes the same causes of action articulated in the first amended complaint, but in regard to only eight projects done between 2001 and 2013. In September 2014, the Colstrip owners filed an answer to the second amended complaint. Discovery closed in the first quarter of 2015, and in April, the plaintiffs indicated they intend to pursue claims related to only four of the remaining projects. The case has been bifurcated as to liability and remedy, and the liability trial is currently set for May 2016. A trial date with respect to remedy, if there is a finding of liability, has not been scheduled. Notice of Intent to File Suit In October 2014, Talen Energy received a notice letter from the Chesapeake Bay Foundation (CBF) alleging violations of the Clean Water Act and Pennsylvania Clean Streams Law at the Brunner Island generation plant. The letter was sent to Brunner Island, LLC and the PADEP and is intended to provide notice of the alleged violations and CBF's intent to file suit in Federal court after expiration of the 60 day statutory notice period. Among other things, the letter alleges that Brunner Island, LLC failed to comply with the terms of its National Pollutant Discharge Elimination System permit and associated regulations related to the application of nutrient credits to the facility's discharges of nitrogen into the Susquehanna River. The letter also alleges that PADEP has failed to ensure that credits generated from nonpoint source pollution reduction activities that Brunner Island, LLC applies to its discharges meet the eligibility and certification requirements under PADEP's nutrient trading program regulations. If a lawsuit is filed by CBF, Talen Energy would expect CBF to seek injunctive relief, monetary penalties, fees and costs of litigation. Montana Regional Haze In September 2012, the EPA Region 8 developed a regional haze Federal Implementation Plan (FIP) for Montana. The final FIP assumed no additional controls for Corette or Colstrip Units 3 and 4, but proposed stricter limits for Corette and Colstrip Units 1 and 2. Talen Montana was meeting these stricter permit limits at Corette without any significant changes to operations, although other requirements led to the suspension of operations and retirement of Corette in March 2015. The stricter limits at Colstrip Units 1 and 2 would require additional controls to meet more stringent nitrogen oxides and sulfur dioxide limits, the cost of which could be significant. Both Talen Montana and environmental groups appealed the final FIP to the U.S. Court of Appeals for the Ninth Circuit where oral argument was heard in May 2014. On June 9, 2015, the Ninth Circuit issued a decision that vacated as arbitrary and capricious the portions of the FIP setting stricter emissions limits for Colstrip Units 1 and 2 and Corette. The Ninth Circuit upheld the EPA's decision not to require further emissions reductions at Colstrip Units 3 and 4. The Ninth Circuit opinion requires the EPA to now reissue a FIP that is consistent with the opinion. Talen Energy does not anticipate a material impact to its financial condition or results of operations from this recent decision. Colstrip Wastewater Facility Administrative Order on Consent Talen Montana is party to an Administrative Order on Consent (AOC) with the MDEQ related to operation of the wastewater facilities at the Colstrip power plant. In September 2012, Earthjustice, on behalf of Sierra Club, MEIC, and the National Wildlife Federation, filed an affidavit under Montana's Major Facility Siting Act (MFSA) that sought review of the AOC by Montana's Board of Environmental Review. Talen Montana elected to have this proceeding conducted in Montana state district court, and in October 2012, Earthjustice filed a petition for review in Montana state district court in Rosebud County. This matter was stayed in December 2012 pending the outcome of separate litigation where the same environmental groups challenged the AOC in a writ of mandamus. That litigation was resolved in May 2013 when defendants Talen Montana and MDEQ won their motions to dismiss the matter, and the environmental groups did not appeal. In April 2014, Earthjustice filed successful motions for leave to amend the petition for review and to lift the stay. Talen Montana and the MDEQ responded to the amended petition and filed partial motions to dismiss in July 2014, which were denied in October 2014. Discovery closed in October 2015, and a bench trial is set for April 2016. Regulatory Matters Talen Energy operates in a highly regulated industry and is subject to regulation by various federal and state agencies and in the various regions where it conducts business. In addition to the regulatory issues discussed below, Talen Energy and its subsidiaries are party to other regulatory proceedings arising in the ordinary course of business or have other regulatory exposure. Other than as described below, in the opinion of management based upon information currently available to Talen Energy, while the outcome of these regulatory matters and proceedings is uncertain, the likely results are not expected, either individually or in the aggregate, to have a material adverse effect on Talen Energy's financial condition or results of operations, although the effect could be material to Talen Energy's results of operations in any interim reporting period. Proposed Legislation - Pacific Northwest In the first quarter of 2015, legislation was proposed in the State of Washington to provide a means of cost recovery to utility owners of coal-fired generating facilities who commit to retire such facilities. Talen Energy cannot predict whether any legislation seeking to achieve these objectives will be enacted. Were such legislation to be enacted as proposed, the resulting laws would not be expected to have a material adverse effect on Talen Energy's financial condition or results of operation. New Jersey Capacity Legislation In January 2011, New Jersey enacted a law (the Act) that Talen Energy believes would intervene in the wholesale capacity market to create incentives for the development of new, in-state electricity generation facilities even when, under the FERC-approved PJM economic model, such new generation would not be economic. The Act could have the effect of depressing capacity prices in PJM in the short term, which could impact Talen Energy's revenues, and also could harm the long-term ability of the PJM capacity market to encourage necessary generation investment throughout PJM. In February 2011, certain Talen Energy subsidiaries and several other companies filed a complaint in U.S. District Court in New Jersey challenging the Act on the grounds that it violates the Supremacy and Commerce clauses of the U.S. Constitution and requesting relief barring implementation. In October 2013, the U.S. District Court in New Jersey issued a decision finding the Act unconstitutional under the Supremacy Clause on the grounds that it infringes upon the FERC's exclusive authority to regulate the wholesale sale of electricity in interstate commerce. The decision was appealed to the U.S. Court of Appeals for the Third Circuit (Third Circuit) by CPV Power Development, Inc., Hess Newark, LLC and the State of New Jersey (the Appellants). In September 2014, the Third Circuit affirmed the District Court's decision. In December 2014, the Appellants filed a petition for certiorari before the U.S. Supreme Court. In March 2015, the U.S. Supreme Court requested the U. S. Solicitor General to submit briefs expressing its views as to the issues raised in this case. In September 2015, the U.S. Solicitor General filed a brief expressing the view of the United States that the case was rightly decided and that the petition for certiorari should be denied. Talen Energy believes, though no assurances can be given, that the proceeding may be delayed pending the outcome of the Maryland Public Service Commission (MD PSC) action described below. Based upon information currently available to it, Talen Energy cannot estimate a range of reasonably possible losses, if any, related to this matter. Maryland Capacity Order In April 2012, the MD PSC ordered (Order) three electric utilities in Maryland to enter into long-term contracts to support the construction of new electricity generating facilities in Maryland, the intent of which, Talen Energy believed, was to encourage the construction of new generation even when, under the FERC-approved PJM economic model, such new generation would not be economic. The MD PSC action could have the effect of depressing capacity prices in PJM in the short term, which could impact Talen Energy's revenues, and also could harm the long-term ability of the PJM capacity market to encourage necessary generation investment throughout PJM. In April 2012, Talen Energy subsidiaries and several other companies filed a complaint in U.S. District Court (District Court) in Maryland challenging the Order on the grounds that it violates the Supremacy and Commerce clauses of the U.S. Constitution, and requested declaratory and injunctive relief barring implementation of the Order by the MD PSC Commissioners. In September 2013, the District Court issued a decision finding the order unconstitutional under the Supremacy Clause on the grounds that it infringes upon the FERC's exclusive authority to regulate the wholesale sale of electricity in interstate commerce. The decision was appealed to the U.S. Court of Appeals for the Fourth Circuit (Fourth Circuit) by CPV Power Development, Inc. and the State of Maryland (the Appellants). In June 2014, the Fourth Circuit affirmed the District Court's opinion and subsequently denied the Appellants' motion for rehearing. In December 2014, the Appellants filed a petition for certiorari before the U.S. Supreme Court. In March 2015, the U.S. Supreme Court requested the U.S. Solicitor General to submit briefs expressing its views as to the issues raised in this case. In September 2015, the U.S. Solicitor General filed a brief expressing the view of the United States that the case was rightly decided and that the petition for certiorari should be denied. In October 2015, the U.S. Supreme Court granted certiorari of the case, and briefing and oral arguments are being scheduled. Based upon information currently available to it, Talen Energy cannot estimate a range of reasonable possible losses, if any, related to this matter. Pacific Northwest Markets Talen Energy Marketing and Talen Montana made spot market bilateral sales of power in the Pacific Northwest during the period from December 2000 through June 2001. Several parties subsequently claimed refunds at FERC as a result of these sales. In June 2003, the FERC terminated proceedings to consider whether to order refunds for spot market bilateral sales made in the Pacific Northwest, including sales made by Talen Montana, during the period December 2000 through June 2001. In August 2007, the U.S. Court of Appeals for the Ninth Circuit reversed the FERC's decision and ordered the FERC to consider additional evidence. In October 2011, the FERC initiated proceedings to consider additional evidence. In June 2015, the United States Court of Appeals for the Ninth Circuit held oral arguments on an appeal from the FERC's October 2011 order setting out the remand process that the FERC has followed from 2011 to the present. A decision from the Ninth Circuit is expected before the end of 2015. In July 2012, Talen Montana and the City of Tacoma, one of the two parties claiming refunds at FERC, reached a settlement whereby Talen Montana paid $75 thousand to resolve the City of Tacoma's $23 million claim. The settlement does not resolve the remaining claim outstanding by the City of Seattle for approximately $50 million . Hearings before a FERC Administrative Law Judge (ALJ) regarding the City of Seattle's refund claims were completed in October 2013 and briefing was completed in January 2014. In March 2014, the ALJ issued an initial decision denying the City of Seattle's complaint against Talen Montana. In May 2015, the FERC issued an order affirming the ALJ's March 2014 decision. Although Talen Energy and its subsidiaries believe they have not engaged in any improper trading or marketing practices affecting the Pacific Northwest markets, Talen Energy cannot predict the outcome of the above-described proceedings or whether any subsidiaries will be the subject of any additional governmental investigations or named in other lawsuits or refund proceedings. Consequently, Talen Energy cannot estimate a range of reasonably possible losses, if any, related to this matter. Electricity - Reliability Standards The NERC is responsible for establishing and enforcing mandatory reliability standards (Reliability Standards) regarding the bulk power system. The FERC oversees this process and independently enforces the Reliability Standards. The Reliability Standards have the force and effect of law and apply to certain users of the bulk power electricity system, including electric utility companies, generators and marketers. Under the Federal Power Act, the FERC may assess civil penalties of up to $1 million per day, per violation, for certain violations. Talen Energy monitors its subsidiaries' compliance with the Reliability Standards and continues to self-report potential violations of certain applicable reliability requirements and submit accompanying mitigation plans, as required. The resolution of a number of potential violations is pending. In the course of implementing their programs to ensure compliance with the Reliability Standards by those Talen Energy subsidiaries subject to the standards, certain other instances of potential non-compliance may be identified from time to time. Talen Energy cannot predict the outcome of these matters, and cannot estimate a range of reasonably possible losses, if any. Environmental Matters Due to the environmental issues discussed below or other environmental matters, it may be necessary for Talen Energy to modify, curtail, replace or cease operation of certain facilities or performance of certain operations to comply with statutes, regulations and other requirements of regulatory bodies or courts. In addition, legal challenges to environmental permits or rules add to the uncertainty of estimating the future cost of these permits and rules. Other than as described below, in the opinion of management based upon information currently available to Talen Energy, while the outcome of these environmental matters and proceedings is uncertain, the likely results are not expected, either individually or in the aggregate, to have a material adverse effect on Talen Energy's financial condition or results of operations, although the effect could be material to Talen Energy's results of operations in any interim reporting period. Air CSAPR The EPA's CSAPR addresses the interstate transport of fine particulates and ozone by regulating emissions of sulfur dioxide and nitrogen oxide. In accordance with an October 2014 D.C. Circuit Court of Appeals decision, CSAPR establishes interstate allowance trading programs for sulfur dioxide and nitrogen oxide emissions from fossil-fueled plants in two phases: Phase 1 trading commenced in January 2015, and Phase 2 trading is expected to commence in 2017. Legal challenges to CSAPR are on-going in federal and state court and the EPA has committed to issuing a new proposed transport rule addressing nitrogen oxide emissions to satisfy the Clean Air Act good neighbor provisions with respect to the 2008 ozone NAAQS by the end of 2015. Although Talen Energy does not currently anticipate significant costs to comply with these programs, changes in market or operating conditions, or significant regulatory changes, could result in impacts that are greater than anticipated. National Ambient Air Quality Standards In 2008, the EPA revised downward the National Ambient Air Quality Standard (NAAQS) for ozone. As a result, states in the ozone transport region (OTR), including Pennsylvania, Maryland and New Jersey, are required by the Clean Air Act to impose additional reductions in nitrogen oxide emissions based upon reasonably available control technologies (RACT). In 2015, the PADEP is expected to finalize a RACT rule requiring some fossil-fueled plants to operate at more stringent nitrogen oxide emission rates. Maryland coal plants operated at reduced nitrogen oxide emission rates during the 2015 ozone season as a result of an emergency action issued by the Governor (which later became a final rule), and the MDE is developing post-2015 nitrogen oxide regulations for Maryland coal plants that could also be finalized by the end of 2015. MDE and the Governor have been sued by some environmental groups on the grounds that nitrogen oxide regulations developed under the prior Administration, and later withdrawn, were a final agency action. In October 2015, the EPA released a final rule that strengthens the NAAQS for ozone. This could lead to even further nitrogen oxide reductions for Talen Energy's fossil-fueled plants within, and outside of, the OTR. State and federal efforts to address interstate transport issues associated with ozone national ambient air quality standards, including increased pressure by state environmental agencies to further reduce nitrogen oxide emissions from plants with selective catalytic reduction technology, could potentially lead to further emission reductions. In 2010, the EPA finalized a more stringent NAAQS for sulfur dioxide and required states to identify areas that meet the standard and areas that are in "non-attainment" or are unclassifiable. In July 2013, the EPA finalized non-attainment designations for parts of the country where attainment is due by 2018. States are working on designations for other areas pursuant to a consent decree between the EPA and Sierra Club approved in March 2015 with 2017 or 2020 deadlines, depending on which designation methodology (modeling or monitoring) is selected. In December 2012, the EPA issued final rules that tighten the annual NAAQS for fine particulates. The rules were challenged by industry groups, and in May 2014 the D.C. Circuit Court of Appeals upheld them. In January 2015, the EPA published a final rule establishing area designations under the standard. Non-attainment areas in Pennsylvania were identified; however, the EPA subsequently approved state implementation plan revisions that improved these classifications. Until final rules are promulgated, all non-attainment designations are finalized and state compliance plans are developed, Talen Energy cannot predict the ultimate outcome of the new NAAQS for ozone, sulfur dioxide and particulate matter on its fleet or plants or whether they may have a material adverse effect on Talen Energy's financial condition or results of operations. Talen Energy anticipates that some of the measures required for compliance with the CSAPR (as discussed above), or the MATS and Regional Haze Rules (as discussed below), will help to achieve compliance. MATS In February 2012, the EPA finalized a rule (known as the MATS Rule) requiring reductions of mercury and other hazardous air pollutants from fossil-fuel fired power plants by April 2015 with one -and two -year extension opportunities. The rule was challenged by industry groups and states and was upheld by the D.C. Circuit Court of Appeals in April 2014. The U.S. Supreme Court agreed to review this decision and issued its decision in June 2015 finding that the EPA acted unreasonably by refusing to consider costs when determining whether the MATS regulation was appropriate and necessary. The MATS Rule remains in effect pending further actions by the D.C. Circuit Court of Appeals and the EPA. Apart from the EPA's MATS Rule, several states, including Montana and Maryland, have enacted regulations requiring mercury emission reductions from coal plants in those states. Regional Haze and Visibility The EPA's regional haze programs were developed under the Clean Air Act to eliminate man-made visibility degradation by 2064. Under the programs, states are required to make reasonable progress every decade, through the application, among other things, of Best Available Retrofit Technology (BART) on power plants commissioned between 1962 and 1977. The primary power plant emissions affecting visibility are sulfur dioxide, nitrogen oxides and particulates. To date, the focus of regional haze regulation has been primarily on the western U.S. The EPA is also working to address regional haze in Texas. A federal plan was proposed in December 2014 with an emphasis on coal plants. Minimal impacts are anticipated to Talen's gas fleet in Texas. As for the eastern U.S., the EPA had determined that region-wide reductions under the CSAPR trading program could, in most instances, be utilized under state programs to satisfy BART requirements for sulfur dioxide and nitrogen oxides. However, the EPA's determination is being challenged by environmental groups. In September 2015, the Third Circuit Court of Appeals vacated portions of the EPA's approval of Pennsylvania's regional haze State Implementation Plan and remanded to EPA the rule for further consideration. Talen Energy is unable to determine at this time if the future impacts of Regional Haze on Talen Energy plants in the eastern U.S. will have a material adverse effect on Talen Energy's financial condition or results of operations. See "Legal Matters" above for information on a legal decision recently issued by the Ninth Circuit Court of Appeals in a case challenging the EPA's final Regional Haze Federal Implementation Plan for Montana. New Source Review (NSR) The EPA has continued its NSR enforcement efforts targeting coal-fired generating plants. The EPA has alleged that modification of these plants has increased their emissions and, consequently, that they are subject to stringent NSR requirements under the Clean Air Act. Talen Energy has responded to several information requests from the EPA, but has received no further substantive communications from the EPA related to those requests since providing their responses. See "Legal Matters" above for information on a lawsuit filed by environmental groups in March 2013 against Talen Montana and other owners of Colstrip related to NSR. Climate Change Physical effects associated with climate change could include the impact of changes in weather patterns, such as storm frequency and intensity, and the resultant potential damage to Talen Energy's generation assets, as well as impacts on Talen Energy's customers. In addition, changed weather patterns could potentially reduce annual rainfall in areas where Talen Energy has hydroelectric generating facilities or where river water is used to cool its fossil and nuclear powered generators. Federal and state initiatives to prepare energy assets and infrastructure for the impacts of climate change, such as those actions driven by President Obama's 2013 Climate Action Plan (discussed further below), could result in binding obligations to protect these assets. Talen Energy cannot currently predict whether its businesses will experience these potential risks or whether any related costs will have a material adverse effect on Talen Energy's financial condition or results of operations. GHG Regulations & Tort Litigation As a result of the April 2007 U.S. Supreme Court decision that the EPA has authority under the Clean Air Act to regulate carbon dioxide emissions from new motor vehicles, in April 2010, the EPA and the U.S. Department of Transportation issued new light-duty vehicle emissions standards that applied beginning with 2012 model year vehicles. The EPA also clarified that this standard, beginning in 2011, authorized regulation of carbon dioxide emissions from stationary sources under the NSR and Title V operating permit provisions of the Clean Air Act. The EPA's rules were challenged in court and in June 2014 the U.S. Supreme Court ruled that the EPA has the authority to regulate carbon dioxide emissions under these provisions of the Clean Air Act, but only for stationary sources that would otherwise have been subject to these provisions due to significant increases in emissions of other regulated pollutants. As a result, any new sources or major modifications to an existing GHG source causing a net significant increase in carbon dioxide emissions must comply with BACT permit limits for carbon dioxide if it would otherwise be subject to BACT or lowest achievable emissions rate limits due to significant increases in other regulated pollutants. EPA is expected to propose a de minimis threshold for such permits in June 2016. In June 2013, President Obama released his Climate Action Plan reiterating the goal of reducing GHG emissions in the U.S. through such actions as regulating power plant emissions, promoting increased use of renewables and clean energy technology, and establishing more restrictive energy efficiency standards. Since that time, the EPA has proposed and finalized regulations for existing and new power plants. The EPA's final rules addressing GHG emissions for new and existing power plants were published in the Federal Register in October 2015 along with a proposed federal implementation plan that would apply to any states that fail to submit an acceptable state implementation plan for the existing plant rule. The new and existing plant rules are being challenged in federal court. Comments are due to the EPA on the federal implementation plan proposal by January 2016. Implementation of the new and existing power plant rules could have a significant industry-wide impact, but at this time Talen Energy is unable to determine if the rules will have a material adverse effect on Talen Energy's financial condition or results of operations. A number of lawsuits have been filed asserting common law claims including nuisance, trespass and negligence against various companies with GHG emitting plants and, although the decided cases to date have not sustained claims brought on the basis of these theories of liability, the law remains unsettled on these claims. Renewable Energy Legislation Legislation introduced and/or under development in states where Talen Energy operates or competes for energy supply could have a significant impact on Talen Energy's competitive and financial positions. There are financial, regulatory and operational uncertainties related to the implementation of such renewable energy mandates that will need to be resolved before any impacts can be meaningfully estimated and, as a result, at this time Talen Energy is unable to determine if such renewable energy mandates will have a material adverse effect on Talen Energy's financial condition or results of operations. Water/Waste Coal Combustion Residuals (CCRs) In April 2015, the EPA published its final rule regulating CCRs. CCRs include fly ash, bottom ash and sulfur dioxide scrubber wastes. The rule became effective in October 2015. It imposes extensive new requirements, including location restrictions, design and operating standards, groundwater monitoring and corrective action requirements and closure and post-closure care requirements on CCR impoundments and landfills that are located at active power plants and not closed. Under the rule, the EPA will regulate CCRs as non-hazardous under Subtitle D of RCRA and allow beneficial use of CCRs, with some restrictions. This self-implementing rule requires posting of compliance documentation on a publicly accessible website and is only enforceable through citizen suits. Talen Energy expects that its plants using surface impoundments for management and disposal of CCRs, or that previously managed CCRs and continue to manage wastewaters, will be most impacted by the rule. Requirements for covered CCR impoundments and landfills include commencement or completion of closure activities generally between three and ten years from certain triggering events. Talen Energy anticipates incurring capital or operation and maintenance costs prior to that time to address other requirements of the rule, such as groundwater monitoring and disposal facility modifications, or to implement various compliance strategies. The final CCR rule is being challenged in federal court. Talen Energy continues to review the rule and evaluate financial and operational impacts. During the nine months ended September 30, 2015 , $36 million of increases to existing AROs were recorded. Further changes to AROs may be required as estimates are refined and compliance with the rule continues. See Note 16 for information on AROs. Effluent Limitations Guidelines (ELGs) and Standards The EPA's final ELG regulations

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2015
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Prior to the spinoff, PPL Electric and PPL Services were affiliates of Talen Energy. The disclosures below provide information regarding transactions that occurred prior to June 1, 2015. After June 1, 2015, transactions with PPL Electric and PPL Services, or any other PPL subsidiaries are not related party transactions. PLR Contracts/Sales of Accounts Receivable PPL Electric holds competitive solicitations for PLR generation supply. Talen Energy Marketing has been awarded a portion of the PLR generation supply through these competitive solicitations. The sales between Talen Energy Marketing and PPL Electric prior to May 31, 2015 and during the three and nine months ended September 30, 2014 are included in the Statements of Income as "Wholesale energy to affiliate" by Talen Energy. PPL Electric's customers may choose an alternative supplier for their generation supply. As part of a PUC-approved purchase of accounts receivable program, PPL Electric purchases certain accounts receivable from alternative electricity suppliers (including Talen Energy Marketing) at a discount. For the five month period up to the spinoff included in the nine months ended September 30, 2015 , Talen Energy Marketing sold accounts receivable to PPL Electric of $146 million , compared with $77 million and $261 million during the three and nine month period ended September 30, 2014 . Losses resulting from the sales of accounts receivable to PPL Electric during these periods were not material. Support Costs Prior to the spinoff, Talen Energy was provided with administrative, management and support services, primarily from PPL Services. Where applicable, the costs of these services were charged to Talen Energy Supply as direct support costs. General costs that could not be directly attributed to a specific affiliate were allocated and charged to the respective affiliates, including Talen Energy Supply, as indirect support costs. PPL Services used a three-factor methodology that includes the affiliates invested capital, operation and maintenance expenses and number of employees to allocate indirect costs. Talen Energy Supply was charged, primarily by PPL Services, the following amounts for the periods ended September 30, and believes these amounts were reasonable at the time, including amounts applied to accounts that are further distributed between capital and expense. Three Months Nine Months 2015 2014 2015 2014 $ — $ 49 $ 67 $ 161 Transition Services Agreement As part of the spinoff transaction, Talen Energy Supply entered into a TSA with Topaz Power Management, LP (an affiliate of Riverstone) for certain business administrative services. For the three and nine months ended September 30, 2015 , these costs, which are recorded in "Operation and maintenance" on the Statement of Income, were $4 million and $5 million . Gas Supply Contract A subsidiary of Jade has a gas supply contract in place with TrailStone NA Logistics LLC (TrailStone), an affiliate of Riverstone, under which TrailStone supplies gas to the generation facilities owned by Jade. For the three and nine months ended September 30, 2015 , Talen Energy incurred $26 million and $32 million of costs for these gas purchases, which are recorded in "Fuel" on the Statement of Income. Other See Note 5 , Note 8 , and Note 9 for discussions regarding intercompany allocations associated with income taxes, stock-based compensation, and defined benefits.

Other Income (Expense) - net

Other Income (Expense) - net	9 Months Ended
	Sep. 30, 2015
Other Nonoperating Income (Expense) [Abstract]
Other Income (Expense) - net	Other Income (Expense) - net Talen Energy's "Other Income (Expense) - net" for the three and nine months ended September 30, 2015 and 2014 was primarily earnings on securities in NDT funds.

Fair Value Measurements and Cre

Fair Value Measurements and Credit Concentration	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements and Credit Concentration	Fair Value Measurements and Credit Concentration Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (an exit price). A market approach (generally, data from market transactions), an income approach (generally, present value techniques and option-pricing models), and/or a cost approach (generally, replacement cost) are used to measure the fair value of an asset or liability, as appropriate. These valuation approaches incorporate inputs such as observable, independent market data and/or unobservable data that management believes are predicated on the assumptions market participants would use to price an asset or liability. These inputs may incorporate, as applicable, certain risks such as nonperformance risk, which includes credit risk. The fair value of a group of financial assets and liabilities is measured on a net basis. Transfers between levels are recognized at end-of-reporting-period values. During the three and nine months ended September 30, 2015 and 2014 , there were no transfers between Level 1 and Level 2. See Talen Energy Supply's Note 1 to the Financial Statements in the 2015 Prospectus for information on the levels in the fair value hierarchy. Recurring Fair Value Measurements The assets and liabilities measured at fair value were: September 30, 2015 December 31, 2014 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 648 $ 648 $ — $ — $ 352 $ 352 $ — $ — Restricted cash and cash equivalents (a) 83 83 — — 193 193 — — Price risk management assets: Energy commodities 802 — 739 63 1,318 6 1,171 141 Total price risk management assets 802 — 739 63 1,318 6 1,171 141 NDT funds: Cash and cash equivalents 13 13 — — 19 19 — — Equity securities U.S. large-cap 581 433 148 — 611 454 157 — U.S. mid/small-cap 84 35 49 — 89 37 52 — Debt securities U.S. Treasury 94 94 — — 99 99 — — U.S. government sponsored agency 7 — 7 — 9 — 9 — Municipality 81 — 81 — 76 — 76 — Investment-grade corporate 49 — 49 — 42 — 42 — Other 4 — 4 — 3 — 3 — Receivables (payables), net — (3 ) 3 — 2 — 2 — Total NDT funds 913 572 341 — 950 609 341 — Auction rate securities (b) 6 — — 6 8 — — 8 Total assets $ 2,452 $ 1,303 $ 1,080 $ 69 $ 2,821 $ 1,160 $ 1,512 $ 149 Liabilities Price risk management liabilities: Energy commodities $ 684 $ — $ 626 $ 58 $ 1,217 $ 5 $ 1,182 $ 30 Total price risk management liabilities $ 684 $ — $ 626 $ 58 $ 1,217 $ 5 $ 1,182 $ 30 (a) Current portion is included in "Restricted cash and cash equivalents" and long-term portion is included in "Other noncurrent assets" on the Balance Sheets. (b) Included in "Other investments" on the Balance Sheets. A reconciliation of net assets and liabilities classified as Level 3 for the periods ended September 30, 2015 is as follows: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Three Months Nine Months Energy Commodities, net Auction Rate Securities Total Energy Commodities, net Auction Rate Securities Total Balance at beginning of period $ 10 $ 7 $ 17 $ 111 $ 8 $ 119 Total realized/unrealized gains (losses) Included in earnings (7 ) — (7 ) (148 ) — (148 ) Purchases (a) — — — (39 ) — (39 ) Sales — (1 ) (1 ) 65 (2 ) 63 Settlements (9 ) — (9 ) (6 ) — (6 ) Transfers into Level 3 — — — 10 — 10 Transfers out of Level 3 11 — 11 12 — 12 Balance at end of period $ 5 $ 6 $ 11 $ 5 $ 6 $ 11 (a) Positions acquired through the acquisition of RJS Power. A reconciliation of net assets and liabilities classified as Level 3 for the periods ended September 30, 2014 is as follows: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Three Months Nine Months Energy Commodities, net Auction Rate Securities Total Energy Commodities, net Auction Rate Securities Total Balance at beginning of period $ 74 $ 13 $ 87 $ 24 $ 16 $ 40 Total realized/unrealized gains (losses) Included in earnings (84 ) — (84 ) (147 ) — (147 ) Purchases — — — (6 ) — (6 ) Sales 67 (3 ) 64 67 (6 ) 61 Settlements (37 ) — (37 ) 82 — 82 Balance at end of period $ 20 $ 10 $ 30 $ 20 $ 10 $ 30 The significant unobservable inputs used in and quantitative information about the fair value measurement of assets and liabilities classified as Level 3 are as follows: September 30, 2015 Talen Energy Fair Value, net Asset (Liability) Valuation Technique Significant Unobservable Input(s) Range (Weighted Average) (a) Energy commodities Natural gas contracts (b) $ 31 Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (37%) Power sales contracts (c) (2 ) Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (70%) FTR purchase contracts (d) (1 ) Discounted cash flow Historical settled prices used to model forward prices 100% (100%) Heat rate call options (e) (21 ) Discounted cash flow Proprietary model used to calculate forward prices 100% (100%) CRR purchase contracts (g) (2 ) Discounted cash flow Proprietary model used to calculate forward prices 100% (100%) Auction rate securities (f) 6 Discounted cash flow Modeled from SIFMA Index 52% - 57% (54%) December 31, 2014 Talen Energy Fair Value, net Asset (Liability) Valuation Technique Significant Unobservable Range (Weighted Average) (a) Energy commodities Natural gas contracts (b) $ 59 Discounted cash flow Proprietary model used to calculate forward prices 11% - 100% (52%) Power sales contracts (c) (1 ) Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (59%) FTR purchase contracts (d) 3 Discounted cash flow Historical settled prices used to model forward prices 100% (100%) Heat rate call options (e) 50 Discounted cash flow Proprietary model used to calculate forward prices 23% - 51% (45%) Auction rate securities (f) 8 Discounted cash flow Modeled from SIFMA Index 51% - 69% (63%) (a) The range and weighted average represent the percentage of fair value derived from the unobservable inputs. (b) As the forward price of natural gas increases/(decreases), the fair value of purchase contracts increases/(decreases). As the forward price of natural gas increases/(decreases), the fair value of sales contracts (decreases)/increases. (c) As forward market prices increase/(decrease), the fair value of contracts (decreases)/increases. As volumetric assumptions for contracts in a gain position increase/(decrease), the fair value of contracts increases/(decreases). As volumetric assumptions for contracts in a loss position increase/(decrease), the fair value of the contracts (decreases)/increases. (d) As the forward implied spread increases/(decreases), the fair value of the contracts increases/(decreases). (e) The proprietary model used to calculate fair value incorporates market heat rates, correlations and volatilities. As the market implied heat rate increases/(decreases), the fair value of purchased calls increases/(decreases). As the market implied heat rate increases/(decreases), the fair value of sold calls (decreases)/increases. (f) The model used to calculate fair value incorporates an assumption that the auctions will continue to fail. As the modeled forward rates of the SIFMA Index increase/(decrease), the fair value of the securities increases/(decreases). (g) As the forward implied spread increases/(decreases), the fair value of the contracts increases/(decreases). Net gains and losses on assets and liabilities classified as Level 3 and included in earnings for the periods ended September 30 are reported in the Statements of Income as follows: Three Months Energy Commodities, net Wholesale Energy Retail Energy Energy Purchases 2015 2014 2015 2014 2015 2014 Total gains (losses) included in earnings $ 2 $ (102 ) $ (1 ) $ 16 $ (8 ) $ 2 Change in unrealized gains (losses) relating 8 6 12 13 (1 ) 1 Nine Months Energy Commodities, net Wholesale Energy Retail Energy Energy Purchases 2015 2014 2015 2014 2015 2014 Total gains (losses) included in earnings $ (108 ) $ (133 ) $ (33 ) $ (35 ) $ (7 ) $ 21 Change in unrealized gains (losses) relating (31 ) 5 9 (12 ) (5 ) (3 ) Price Risk Management Assets/Liabilities - Energy Commodities Energy commodity contracts are generally valued using the income approach, except for exchange-traded derivative contracts, which are valued using the market approach and are classified as Level 1. Level 2 contracts are valued using inputs which may include quotes obtained from an exchange (where there is insufficient market liquidity to warrant inclusion in Level 1), binding and non-binding broker quotes, prices posted by ISOs or published tariff rates. Furthermore, independent quotes are obtained from the market to validate the forward price curves. Energy commodity contracts include forwards, futures, swaps, options and structured transactions and may be offset with similar positions in exchange-traded markets. To the extent possible, fair value measurements utilize various inputs that include quoted prices for similar contracts or market-corroborated inputs. In certain instances, these contracts may be valued using models, including standard option valuation models and other standard industry models. When the lowest level inputs that are significant to the fair value measurement of a contract are observable, the contract is classified as Level 2. When unobservable inputs are significant to the fair value measurement, a contract is classified as Level 3. Level 3 contracts are valued using Talen Energy's proprietary models which may include significant unobservable inputs such as delivery at a location where pricing is unobservable, delivery dates that are beyond the dates for which independent quotes are available, volumetric assumptions, implied volatilities, implied correlations, and market implied heat rates. Forward transactions, including forward transactions classified as Level 3, are analyzed by Talen Energy's Risk Management department. Accounting personnel interpret the analysis quarterly to appropriately classify the fair value measurements in the fair value hierarchy. Valuation techniques are evaluated periodically. Additionally, Level 2 and Level 3 fair value measurements include adjustments for credit risk based on Talen Energy's own creditworthiness (for net liabilities) and its counterparties' creditworthiness (for net assets). Talen Energy's credit department assesses all reasonably available market information which is used by accounting personnel to calculate the credit valuation adjustment. In certain instances, energy commodity contracts are transferred between Level 2 and Level 3. The primary reasons for the transfers during 2015 were changes in the availability of market information and changes in the significance of the unobservable inputs utilized in the valuation of the contracts. NDT Funds The market approach is used to measure the fair value of equity securities held in the NDT funds. • The fair value measurements of equity securities classified as Level 1 are based on quoted prices in active markets. • The fair value measurements of investments in commingled equity funds are classified as Level 2. These fair value measurements are based on firm quotes of net asset values per share, which are not obtained from a quoted price in an active market. The fair value of debt securities is generally measured using a market approach, including the use of pricing models which incorporate observable inputs. Common inputs include benchmark yields, relevant trade data, broker/dealer bid/ask prices, benchmark securities and credit valuation adjustments. When necessary, the fair value of debt securities is measured using the income approach, which incorporates similar observable inputs as well as payment data, future predicted cash flows, collateral performance and new issue data. Auction Rate Securities The fair value of auction rate securities is estimated using an income approach that includes readily observable inputs, such as principal payments and discount curves for bonds with credit ratings and maturities similar to the securities, and unobservable inputs, such as future interest rates that are estimated based on the SIFMA Index, creditworthiness, and liquidity assumptions driven by the impact of auction failures. The probability of realizing losses on these securities is not significant. When the present value of future interest payments is significant to the overall valuation, the auction rate securities are classified as Level 3. Auction rate securities are valued by the Treasury department. Accounting personnel interpret the analysis quarterly to classify the fair value measurements in the fair value hierarchy. Valuation techniques are evaluated periodically. Nonrecurring Fair Value Measurements The following nonrecurring fair value measurements occurred during the periods ended September 30, 2015 and 2014 resulting in asset impairments: Carrying Amount (a) Fair Value Measurements Using Level 3 (b) Pre-tax Loss (c) Kerr Dam Project (March 31, 2014) $ 47 $ 29 $ 18 Sapphire portfolio and C.P. Crane plant (September 30, 2015) 388 266 122 (a) Represents carrying value before fair value measurement. (b) For the Sapphire portfolio, also reflects estimated cost to sell. (c) The impairments on the Kerr Dam Project and Sapphire portfolio are included in "Income (Loss) from Discontinued Operations (net of income taxes)" on the Statement of Income. The impairment on the C.P. Crane plant is included in "Impairments" on the Statement of Income. The significant unobservable inputs used in and the quantitative information about the nonrecurring fair value measurement of assets and liabilities classified as Level 3 are as follows: Fair Value, net Asset (Liability) Valuation Technique Significant Unobservable Input(s) Range (Weighted Average)(a) Kerr Dam Project (March 31, 2014) $ 29 Discounted cash flow Proprietary model used to calculate plant value 38% (38%) Sapphire portfolio and C.P. Crane plant (September 30, 2015) 266 Discounted cash flow Proprietary model used to calculate plant value 100% (100%) (a) The range and weighted average represent the percentage of fair value derived from the unobservable inputs. Kerr Dam Project Talen Montana previously held a joint operating license issued for the Kerr Dam Project. The license extends until 2035 and, between 2015 and 2025, the Confederated Salish and Kootenai Tribes of the Flathead Nation (the Tribes) have the option to purchase, hold and operate the Kerr Dam Project. The parties submitted the issue of the appropriate amount of the conveyance price to arbitration in February 2013. In March 2014, the arbitration panel issued its final decision holding that the conveyance price payable by the Tribes to Talen Montana is $18 million . As a result of the decision, Talen Energy performed a recoverability test on the Kerr Dam Project and recorded an impairment charge. Talen Energy performed an internal analysis using an income approach based on discounted cash flows (a proprietary Talen Energy model) to assess the fair value of the Kerr Dam Project. Assumptions used in the Talen Energy proprietary model were the conveyance price, forward energy price curves, forecasted generation, and forecasted operation and maintenance expenditures that were consistent with assumptions used in the business planning process and a market participant discount rate. Through this analysis, Talen Energy determined the estimated fair value of the Kerr Dam Project at March 31, 2014. The Kerr Dam Project was included in the November 2014 sale of the Talen Montana hydroelectric facilities. See Note 7 for additional information on the sale of the Talen Montana hydroelectric facilities. Sapphire portfolio and C.P. Crane plant In the third quarter of 2015, Talen Energy updated its fundamental pricing models in conjunction with market information gained as a result of the 2018/2019 planning year PJM capacity auction completed in August 2015. As a result, Talen Energy assessed certain long-lived assets for impairment and determined that the C.P. Crane coal-fired plant failed a recoverability test and as a result, recorded an impairment charge based on the plant's estimated fair value at September 30, 2015. Additionally, because the Sapphire portfolio is classified as held for sale and must be carried at the lower of its current carrying value or fair value less cost to sell, Talen Energy used updated cash flow information to calculate the estimated fair value of the Sapphire portfolio at September 30, 2015 and determined a write-down was necessary based on estimated fair value. To estimate the fair value of the Sapphire and C.P. Crane assets, Talen Energy performed an internal analysis primarily using an income approach based on discounted cash flows (a proprietary Talen Energy model) to assess the fair value of these assets. Assumptions used in the Talen Energy proprietary model were the forward energy and capacity price curves, forecasted generation, and forecasted operation, maintenance and capital expenditures and a market participant discount rate. Through this analysis, Talen Energy determined the fair value of the Sapphire portfolio and the C.P. Crane plant at September 30, 2015. See Note 7 for additional information on the discontinued operations classification for the Sapphire portfolio and the pending sale of the C.P. Crane plant. The assets were valued by Talen Energy's financial planning and analysis personnel and accounting personnel interpreted the analysis to appropriately classify the fair value measurements in the fair value hierarchy. Financial Instruments Not Recorded at Fair Value The carrying amounts of long-term debt on the Balance Sheets and its estimated fair values are set forth below. The fair value was estimated using an income approach by discounting future cash flows at estimated current cost of funding rates, which incorporates the credit risk of Talen Energy Supply. Long-term debt is classified as Level 2. September 30, 2015 December 31, 2014 Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt $ 4,030 $ 3,717 $ 2,218 $ 2,204 The carrying value of short-term debt, when outstanding, approximates fair value due to the variable interest rates associated with the short-term debt and is classified as Level 2. Credit Concentration Associated with Financial Instruments Contracts are entered into with many entities for the purchase and sale of energy. When NPNS is elected, the fair value of these contracts is not reflected in the financial statements. However, the fair value of these contracts is considered when committing to new business from a credit perspective. See Note 14 for information on credit policies used to manage credit risk, including master netting arrangements and collateral requirements. At September 30, 2015 , Talen Energy had credit exposure of $554 million from energy trading partners, excluding the effects of netting arrangements, reserves and collateral. As a result of netting arrangements, reserves and collateral, Talen Energy's credit exposure was reduced to $351 million . The top ten counterparties, including their affiliates, accounted for $170 million , or 48% , of these exposures. Nine of these counterparties had an investment grade credit rating from S&P or Moody's and accounted for 91% of the top ten exposures. The remaining counterparty has not been rated by S&P or Moody's, but is current on its obligations.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities Risk Management Objectives Talen Energy has a risk management policy approved by the Talen Energy Corporation Board of Directors to manage market risk associated with commodities, interest rates on debt issuances and foreign exchange (including price, liquidity and volumetric risk) and credit risk (including non-performance risk and payment default risk). A risk management committee, comprised of senior management and chaired by the Director-Risk Management, oversees the risk management function. Key risk control activities designed to ensure compliance with the risk policy include, but are not limited to, credit review and approval, validation of transactions and market prices, verification of risk and transaction limits, VaR analysis, portfolio stress tests, cash flow at risk analysis, EBITDA, free cash flow and credit metric tolerances, sensitivity analysis and daily portfolio reporting. Market Risk Market risk includes the potential loss that may be incurred as a result of price changes associated with a particular financial or commodity instrument as well as market liquidity and volumetric risks. Forward and futures contracts, options, swaps and structured transactions are utilized as part of risk management strategies to minimize unanticipated fluctuations in earnings caused by changes in commodity prices, volumes of full-requirement sales contracts, basis exposure and interest rates. Many of the contracts meet the definition of a derivative. All derivatives are recognized on the Balance Sheets at their fair value, unless NPNS is elected. Talen Energy is subject to market risks, which are actively mitigated through the risk management programs described above. Such risks include: • Commodity price risk, including basis and volumetric risk • Interest rate risk Commodity price risk • Talen Energy is exposed to commodity price risk for energy and energy-related products associated with the sale of electricity from its generating assets and other electricity and gas marketing activities and the purchase of fuel and fuel-related commodities for generating assets, as well as for proprietary trading activities. Interest rate risk • Talen Energy is exposed to interest rate risk associated with forecasted fixed-rate and existing floating-rate debt issuances. Credit Risk Credit risk is the potential loss that may be incurred due to a counterparty's non-performance. Talen Energy is exposed to credit risk from "in-the-money" commodity derivatives with its energy trading partners, which include other energy companies, fuel suppliers, financial institutions and other wholesale and retail customers. The majority of Talen Energy's credit risk stems from commodity derivatives for multi-year contracts for energy sales and purchases. If Talen Energy's counterparties fail to perform their obligations under such contracts and Talen Energy could not replace the sales or purchases at the same or better prices as those under the defaulted contracts, Talen Energy would incur financial losses. Those losses would be recognized immediately or through lower revenues or higher costs in future years, depending on the accounting treatment for the defaulted contracts. Talen Energy has credit policies in place to manage credit risk, including the use of an established credit approval process, daily monitoring of counterparty positions and the use of master netting agreements or provisions. These agreements generally include credit mitigation provisions, such as margin, prepayment or collateral requirements. Talen Energy may request additional credit assurance, in certain circumstances, in the event that the counterparties' credit ratings fall below investment grade or their exposures exceed an established credit limit. See Note 13 for credit concentration associated with energy trading partners. Master Netting Arrangements Net derivative positions on the balance sheets are not offset against the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a payable) under master netting arrangements. Talen Energy's obligation to return counterparty cash collateral under master netting arrangements was $7 million and $ 11 million at September 30, 2015 and December 31, 2014 . Talen Energy did not post any cash collateral under master netting arrangements at September 30, 2015 and December 31, 2014 . See "Offsetting Derivative Investments" below for a summary of derivative positions presented in the balance sheets where a right of setoff exists under these arrangements. Commodity Price Risk (Non-trading) Commodity price risk, including basis and volumetric risk, is among Talen Energy's most significant risks due to the level of investment that Talen Energy maintains in its competitive generation assets. Several factors influence price levels and volatilities. These factors include, but are not limited to, seasonal changes in demand, weather conditions, available generating assets within regions, transportation/transmission availability and reliability within and between regions, market liquidity, and the nature and extent of current and potential federal and state regulations. Talen Energy has a formal hedging program to economically hedge the forecasted purchase and sale of electricity and related fuels for its competitive generation fleet, which has a generation capacity of 15,053 MW (summer rating). Talen Energy's portfolio also includes full-requirement sales contracts and related supply contracts and retail natural gas and electricity sale contracts. The strategies that Talen Energy uses to hedge its full-requirement sales contracts include supplying the energy, capacity and RECs from its generation assets and purchasing energy (at a liquid trading hub or directly at the load delivery zone), capacity and RECs in the market. Talen Energy enters into financial and physical derivative contracts, including forwards, futures, swaps and options, to hedge the price risk associated with electricity, natural gas, oil and other commodities. Certain contracts are non-derivatives or NPNS is elected and therefore they are not reflected in the financial statements until delivery. Talen Energy segregates its non-trading activities into two categories: cash flow hedges and economic activity as discussed below. Cash Flow Hedges Certain derivative contracts have qualified for hedge accounting so that the effective portion of a derivative's gain or loss is deferred in AOCI and reclassified into earnings when the forecasted transaction occurs. In 2015 and 2014, there were no active cash flow hedges and there was no hedge ineffectiveness associated with energy derivatives. At September 30, 2015 , the accumulated net unrecognized after-tax gains (losses) that are expected to be reclassified into earnings during the next 12 months were $14 million . Cash flow hedges are discontinued if it is no longer probable that the original forecasted transaction will occur by the end of the originally specified time periods and any amounts previously recorded in AOCI are reclassified into earnings once it is determined that the hedge transaction is probable of not occurring. There were no such reclassifications for the three and nine months ended September 30, 2015 and 2014 . Economic Activity Many derivative contracts economically hedge the commodity price risk associated with electricity, natural gas, oil and other commodities but do not receive hedge accounting treatment because they were not eligible for hedge accounting or because hedge accounting was not elected. These derivatives hedge a portion of the economic value of Talen Energy's competitive generation assets and competitive full-requirement and retail contracts, which are subject to changes in fair value due to market price volatility and volume expectations. The derivative contracts in this category that existed at September 30, 2015 range in maturity through 2020 . Examples of economic activity may include hedges on sales of nuclear, coal and hydroelectric generation, certain purchase contracts used to supply full-requirement sales contracts, FTRs, CRRs, or basis swaps used to hedge basis risk associated with the sale of competitive generation or supplying full-requirement sales contracts, Spark Spread hedging contracts, retail electric and natural gas activities, and fuel oil swaps used to hedge price escalation clauses in coal transportation and other fuel-related contracts. Talen Energy also uses options, which include the sale of call options and the purchase of put options tied to a particular generating unit. Since the physical generating capacity is owned, price exposure is generally capped at the price at which the generating unit would be dispatched and therefore does not expose Talen Energy to uncovered market price risk. The unrealized gains (losses) for economic activity for the periods ended September 30 were as follows. Three Months Nine Months 2015 2014 2015 2014 Operating Revenues Wholesale energy (a) $ (77 ) $ 299 $ (234 ) $ (581 ) Retail energy (3 ) 2 (25 ) (20 ) Operating Expenses Fuel (3 ) (9 ) 13 (3 ) Energy purchases (a) 130 (217 ) 370 402 (a) In the third quarter of 2015, Talen Energy refined an input used in its valuation technique for certain PJM basis curves as observable inputs became available. This change resulted in the recording of a $30 million net unrealized gain, primarily reflected in "Wholesale energy" revenue on the Statement of Income. Commodity Price Risk (Trading) Talen Energy has a proprietary trading strategy which is utilized to take advantage of market opportunities primarily in its geographic footprint. As a result, Talen Energy may at times create a net open position in its portfolio that could result in losses if prices do not move in the manner or direction anticipated. Net energy trading margins, which are included in "Wholesale energy" on the Statements of Income, were insignificant for the three and nine months ended September 30, 2015 and were insignificant and $58 million for the three and nine months ended September 30, 2014 . Commodity Volumes At September 30, 2015 , the net volumes of derivative (sales)/purchase contracts used in support of the various strategies discussed above were as follows. Volumes (a) Commodity Unit of Measure 2015 (b) 2016 2017 Thereafter Power MWh (13,407,010 ) (29,872,806 ) (1,202,348 ) (795,983 ) Capacity MW-Month (538 ) (878 ) 6 3 Gas MMBtu 61,373,321 98,156,219 15,586,507 19,636,898 FTRs MW-Month 2,023 2,889 — — Oil Barrels 29,795 60,000 — — CRRs MWh 475,320 1,393,430 538,584 — Emission Allowances Tons 2,253,123 — — — (a) Volumes for option contracts factor in the probability of an option being exercised and may be less than the notional amount of the option. (b) Represents balance of the current year. Accounting and Reporting All derivative instruments are recorded at fair value on the Balance Sheet as an asset or liability unless NPNS is elected. NPNS contracts for Talen Energy include certain full-requirement sales contracts, other physical purchase and sales contracts and certain retail energy and physical capacity contracts. Changes in the fair value of derivatives not designated as NPNS are recognized currently in earnings unless specific hedge accounting criteria are met and designated as such. Talen Energy has many physical and financial commodity purchases and sales contracts that economically hedge commodity price risk but do not receive hedge accounting treatment. As such, realized and unrealized gains (losses) on these contracts are recorded currently in earnings. Generally each contract is considered a unit of account and Talen Energy presents gains (losses) on physical and financial commodity sales contracts in "Wholesale energy" or "Retail energy" and (gains) losses on physical and financial commodity purchase contracts in "Fuel" or "Energy purchases" on the Statements of Income. Certain of the economic hedging strategies employed by Talen Energy utilize a combination of financial purchases and sales contracts which are similarly reported gross as an expense and revenue, respectively, on the Statements of Income. Talen Energy records realized hourly net sales or purchases of physical power with PJM in its Statements of Income as "Wholesale energy" if in a net sales position and "Energy purchases" if in a net purchase position. See Talen Energy Supply's Notes 1 and 13 to the Financial Statements in the 2015 Prospectus for additional information on accounting policies related to derivative instruments. The following table presents the fair value and location of commodity derivative instruments not designated as hedging instruments recorded on the Balance Sheets. September 30, 2015 December 31, 2014 Assets Liabilities Assets Liabilities Current: Price Risk Management Assets/Liabilities: $ 576 $ 506 $ 1,079 $ 1,024 Noncurrent: Price Risk Management Assets/Liabilities: 226 178 239 193 Total derivatives $ 802 $ 684 $ 1,318 $ 1,217 The following tables present the pre-tax effect of derivative instruments recognized in income for the periods ended September 30, 2015 . Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Derivative Relationships Location of Gain (Loss) Recognized in Income on Derivative Three Months Nine Months Cash Flow Hedges: Commodity contracts Wholesale energy $ (3 ) $ (3 ) Energy purchases 9 25 Depreciation — 1 Total $ 6 $ 23 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative Three Months Nine Months Commodity contracts Wholesale energy $ 298 $ 328 Retail energy 15 (16 ) Fuel (6 ) (5 ) Energy purchases (183 ) (169 ) Total $ 124 $ 138 The following tables present the pre-tax effect of derivative instruments recognized in income for the periods ended September 30, 2014 . Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Derivative Relationships Location of Gain (Loss) Recognized in Income on Derivative Three Months Nine Months Cash Flow Hedges: Commodity contracts Wholesale energy $ (2 ) $ (1 ) Energy purchases 8 23 Depreciation — 1 Discontinued operations 1 6 Total $ 7 $ 29 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative Three Months Nine Months Commodity contracts Wholesale energy (a) $ 617 $ (2,520 ) Retail energy 18 (34 ) Fuel (8 ) (1 ) Energy purchases (b) (505 ) 1,937 Discontinued operations 2 4 Total $ 124 $ (614 ) (a) The nine month period ended September 30, 2014 includes significant realized and unrealized losses on physical and financial commodity sales contracts due to unusual market and weather volatility. (b) The nine month period ended September 30, 2014 includes significant realized and unrealized gains on physical and financial commodity purchase contracts due to unusual market and weather volatility. Offsetting Derivative Instruments Certain subsidiaries of Talen Energy have master netting arrangements or similar agreements in place including derivative clearing agreements with futures commission merchants (FCMs) to permit the trading of cleared derivative products on one or more futures exchanges. The clearing arrangements permit a FCM to use and apply any property in its possession as a setoff to pay amounts or discharge obligations owed by a customer upon default of the customer and typically do not place any restrictions on the FCM's use of collateral posted by the customer. Certain subsidiaries of Talen Energy also enter into agreements pursuant to which they trade certain energy and other products. Under the agreements, upon termination of the agreement as a result of a default or other termination event, the non-defaulting party typically would have a right to set off amounts owed under the agreement against any other obligations arising between the two parties (whether under the agreement or not), whether matured or contingent and irrespective of the currency, place of payment or place of booking of the obligation. Talen Energy has elected not to offset derivative assets and liabilities and not to offset net derivative positions against the right to reclaim cash collateral pledged (an asset) or the obligation to return cash collateral received (a liability) under derivatives agreements. The table below summarizes the energy commodities derivative positions presented in the balance sheets where a right of setoff exists under these arrangements and related cash collateral received or pledged. Assets Liabilities Eligible for Offset Eligible for Offset Gross Derivative Instruments Cash Collateral Received Net Gross Derivative Instruments Cash Collateral Pledged Net September 30, 2015 $ 802 $ 567 $ 81 $ 154 $ 684 $ 567 $ 16 $ 101 December 31, 2014 $ 1,318 $ 1,060 $ 10 $ 248 $ 1,217 $ 1,060 $ 58 $ 99 Credit Risk-Related Contingent Features Certain derivative contracts contain credit risk-related contingent features which, when in a net liability position, permit the counterparties to require the transfer of additional collateral upon certain decreases in the credit ratings of Talen Energy. Most of these features require the transfer of additional collateral or permit the counterparty to terminate the contract when the applicable credit rating falls below investment grade. Some of these features also allow the counterparty to require additional collateral upon each downgrade in the credit rating at levels that remain above investment grade. In either case, most of these credit contingent features require either immediate payment of the net liability as a termination payment or immediate and ongoing full collateralization on derivative instruments in net liability positions given that Talen Energy's credit rating is currently below investment grade. Additionally, certain derivative contracts contain credit risk-related contingent features that require adequate assurance of performance be provided if the other party has reasonable concerns regarding the performance of Talen Energy's obligation under the contract. A counterparty demanding adequate assurance could require a transfer of additional collateral or other security, including letters of credit, cash and guarantees from a creditworthy entity. This would typically involve negotiations among the parties. However, amounts disclosed below represent assumed immediate payment or immediate and ongoing full collateralization for derivative instruments in net liability positions with "adequate assurance" features. At September 30, 2015 , the value of derivative contracts in a net liability position that contain credit risk-related contingent features was $99 million . Collateral posted on those positions was $103 million , and the additional potential collateral requirements, primarily related to further adequate assurance features were $19 million , which is net of receivables and payables already recorded on the Balance Sheet.

Goodwill and Other Asset Impair

Goodwill and Other Asset Impairments	9 Months Ended
	Sep. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Asset Impairments	Goodwill and Other Asset Impairments U.S. GAAP requires that a long-lived asset (or asset group) be tested for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Similarly, a goodwill impairment test is performed annually or more frequently if events or changes in circumstances indicate that more likely than not the carrying amount of a reporting unit may be greater than its fair value. During the second quarter of 2015, due to the impairment of its investment in PPL Energy Supply recorded by PPL (Talen Energy's former parent) at the time of the spinoff, coupled with, and, primarily driven by, Talen Energy Corporation's stock price at the spinoff date, Talen Energy's management concluded that these factors could be indicators of potential impairment with respect to certain long-lived assets and goodwill. After considering additional information, Talen Energy determined that the undiscounted cash flows for potentially affected long-lived assets would not be directly impacted by these factors and therefore concluded that the undiscounted cash flows continued to exceed the carrying value and no further testing of long-lived assets was necessary in the second quarter. Management also performed an interim goodwill impairment assessment as of June 1, 2015, the spinoff and acquisition date. The goodwill impairment analysis is a two-step process. The first step, used to identify potential impairment, is a comparison of the reporting unit's estimated fair value to its carrying value, including goodwill. If the fair value of the reporting unit exceeds its carrying value, applicable goodwill is not considered to be impaired. If the carrying value exceeds the fair value, there is an indication of impairment and the second step is performed to measure the amount of the impairment, if any. The second step requires a company to calculate an implied fair value of goodwill based on a hypothetical purchase price allocation. The East reporting unit, which is equivalent to the East segment continuing operations, failed step one as of June 1, 2015. The step two analysis was not able to be completed by the filing of the second quarter Form 10-Q. As provided for in the applicable accounting guidance, no goodwill impairment charge was recorded based on management's best estimate at that time, which was confirmed when the second quarter analysis was subsequently completed. In the third quarter of 2015, Talen Energy updated its fundamental pricing models in conjunction with market information gained as a result of the 2018/2019 planning year PJM capacity auction completed in August 2015. As a result, Talen Energy assessed certain long-lived assets for impairment and determined that the C.P. Crane coal-fired plant failed a recoverability test and as a result, recorded an impairment charge based on the plant's estimated fair value at September 30, 2015. Additionally, because the Sapphire portfolio is classified as held for sale and must be carried at the lower of its current carrying value or fair value less cost to sell, Talen Energy used updated cash flow information to calculate the estimated fair value of the Sapphire portfolio at September 30, 2015 and recorded an impairment charge based on estimated fair value. See Note 13 for additional information on these fair value estimates and the resulting non-cash asset impairment charges. In addition, Talen Energy Corporation's stock price declined significantly throughout the third quarter of 2015, indicating a significant change in the financial markets' view of the value of Talen Energy's business and/or the industry in which it operates and potential risks associated with an investment in Talen Energy Corporation's common stock. As a result, Talen Energy management concluded that these factors could be indicators of goodwill impairment and reconsidered certain inputs incorporated in its assessment of fair value of both Talen Energy's overall business and the East reporting unit, where all of the goodwill is assigned. These inputs include risk premiums, growth rates, Talen Energy Corporation's stock price expectations and implied multiples from comparable companies' stock prices. Based on this reassessment, the East reporting unit further declined in fair value, when compared to the value calculated in the second quarter of 2015 and again failed step one as of September 30, 2015. The step two analysis was also completed during the third quarter and resulted in a non-cash goodwill impairment charge of $466 million pre-tax recorded for the East segment included within "Income (Loss) from Continuing Operations" in the Statement of Income for the three and nine months ended September 30, 2015. The impairment charge represented all of the goodwill reflected on the Balance Sheet. Most of the impaired goodwill is not deductible for tax purposes and there is no cash tax benefit related to the impairment. To estimate the fair value of Talen Energy's overall business and the East reporting unit, Talen Energy performed an internal analysis using a combination of a market approach using comparable businesses and an income approach based on discounted cash flows. Assumptions used in the discounted cash flow model, in addition to those discussed above, were the forward energy and capacity price curves, forecasted generation, and forecasted operation, maintenance and capital expenditures and a market participant discount rate. The market approach primarily applies EBITDA multiples, based on the implied market value of comparable publicly traded companies, to Talen Energy's and the East reporting unit's EBITDA to determine estimated fair values. The resulting changes in the carrying amount of Talen Energy's goodwill, all of which was assigned to the East segment, for the nine months ended September 30, 2015 were as follows. Total Balance at December 31, 2014 (a) $ 72 Provisional goodwill recognized during the period (b) 394 Impairment (466 ) Balance at September 30, 2015 (a) $ — (a) There were no accumulated impairment losses related to goodwill at December 31, 2014 and $466 million at September 30, 2015 . (b) Recognized as a result of the acquisition of RJS Power. See Note 7 for additional information.

Asset Retirement Obligations

Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations The changes in the carrying amounts of Talen Energy's AROs were as follows. Balance at December 31, 2014 $ 425 Accretion expense 25 Changes in estimate of cash flow or settlement date 21 Obligations assumed in RJS Power acquisition 11 Obligations incurred 3 Obligations settled (2 ) Balance at September 30, 2015 $ 483 Substantially all of the ARO balances are classified as noncurrent at September 30, 2015 and December 31, 2014 . Talen Energy's most significant ARO recorded relates to the decommissioning of the Susquehanna nuclear plant. See Notes 13 and 17 for additional information on the assets in the NDT funds that are legally restricted for the purposes of settling this ARO.

Available-for-Sale Securities

Available-for-Sale Securities	9 Months Ended
	Sep. 30, 2015
Available-for-sale Securities [Abstract]
Available-for-Sale Securities	Available-for-Sale Securities Securities held by Talen Energy's NDT funds and auction rate securities are classified as available-for-sale. Available-for-sale securities are carried on the Balance Sheets at fair value. Unrealized gains and losses on these securities are reported, net of tax, in OCI or are recognized currently in earnings when a decline in fair value is determined to be other-than-temporary. The specific identification method is used to calculate realized gains and losses. The following table shows the amortized cost, the gross unrealized gains and losses recorded in AOCI and the fair value of Talen Energy's available-for-sale securities. September 30, 2015 December 31, 2014 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value NDT funds: Cash and cash equivalents $ 13 $ — $ — $ 13 $ 19 $ — $ — $ 19 Equity securities 292 373 — 665 283 417 — 700 Debt securities 227 8 — 235 218 11 — 229 Receivables/payables, net — — — — 2 — — 2 Total NDT funds $ 532 $ 381 $ — $ 913 $ 522 $ 428 $ — $ 950 Auction rate securities $ 6 $ — $ — $ 6 $ 8 $ — $ — $ 8 See Note 13 for details on the securities held by the NDT funds. There were no securities with credit losses at September 30, 2015 and December 31, 2014 . The following table shows the scheduled maturity dates of debt securities held at September 30, 2015 . Maturity Less Than 1 Year Maturity 1-5 Years Maturity 6-10 Years Maturity in Excess of 10 Years Total Amortized cost $ 11 $ 89 $ 71 $ 62 $ 233 Fair value 11 91 73 66 241 The following table shows proceeds from and realized gains and losses on sales of available-for-sale securities for the periods ended September 30 . Three Months Nine Months 2015 2014 2015 2014 Proceeds from sales of NDT securities (a) $ 43 $ 47 $ 143 $ 112 Other proceeds from sales — 3 — 6 Gross realized gains (b) 6 9 19 17 Gross realized losses (b) 7 2 16 6 (a) These proceeds are used to pay income taxes and fees related to managing the trust. Remaining proceeds are reinvested in the trust. (b) Excludes the impact of other-than-temporary impairment charges recognized on the Statements of Income.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The after-tax changes in Talen Energy's AOCI by component for the periods ended September 30 were as follows. Unrealized gains (losses) Defined benefit plans Available- for-sale securities Qualifying derivatives Prior service costs Actuarial gain (loss) Total December 31, 2014 $ 202 $ 63 $ 7 $ (295 ) $ (23 ) Amounts arising during the period (21 ) — (4 ) 46 21 Reclassifications from AOCI (1 ) (14 ) (1 ) 12 (4 ) Net OCI during the period (22 ) (14 ) (5 ) 58 17 September 30, 2015 $ 180 $ 49 $ 2 $ (237 ) $ (6 ) December 31, 2013 $ 173 $ 88 $ (4 ) $ (180 ) $ 77 Amounts arising during the period 18 — — — 18 Reclassifications from AOCI (5 ) (18 ) 2 4 (17 ) Net OCI during the period 13 (18 ) 2 4 1 September 30, 2014 $ 186 $ 70 $ (2 ) $ (176 ) $ 78 The following table presents the gains (losses) and related income taxes for reclassifications from Talen Energy's AOCI for the periods ended September 30 . The defined benefit plan components of AOCI are not reflected in their entirety in the statement of income during the periods; rather, they are included in the computation of net periodic defined benefit costs (credits). See Note 9 for additional information. Three Months Nine Months Affected Line Item on the Details about AOCI 2015 2014 2015 2014 Statements of Income Available-for-sale securities $ (1 ) $ 7 $ 3 $ 11 Other Income (Expense) - net Income Taxes — (4 ) (2 ) (6 ) Total After-tax (1 ) 3 1 5 Qualifying derivatives Commodity contracts (3 ) (2 ) (3 ) (1 ) Wholesale energy 9 8 25 23 Energy purchases — 1 — 6 Discontinued operations — — 1 1 Other Total Pre-tax 6 7 23 29 Income Taxes (2 ) (2 ) (9 ) (11 ) Total After-tax 4 5 14 18 Defined benefit plans Prior service costs — (2 ) 1 (4 ) Net actuarial loss (5 ) (1 ) (20 ) (6 ) Total Pre-tax (5 ) (3 ) (19 ) (10 ) Income Taxes 2 1 8 4 Total After-tax (3 ) (2 ) (11 ) (6 ) Total reclassifications during the period $ — $ 6 $ 4 $ 17

New Accounting Guidance Pending

New Accounting Guidance Pending Adoption	9 Months Ended
	Sep. 30, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Guidance Pending Adoption	New Accounting Guidance Pending Adoption Accounting for Revenue from Contracts with Customers In May 2014, the FASB issued accounting guidance that establishes a comprehensive new model for the recognition of revenue from contracts with customers. This model is based on the core principle that revenue should be recognized to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance can be applied using either a full retrospective or modified retrospective transition method. In August 2015, the FASB issued guidance that defers the effective date of the standard by one year, which for public business entities, results in initial application of this guidance in annual reporting periods beginning after December 15, 2017 and interim periods within those years. Entities may early adopt the guidance as of the original effective date of the standard, which for public business entities is annual reporting periods beginning after December 15, 2016. Talen Energy expects to adopt this guidance effective January 1, 2018. Talen Energy is currently assessing the impact of adopting this guidance, as well as the transition method it will use. Reporting Uncertainties about an Entity's Ability to Continue as a Going Concern In August 2014, the FASB issued accounting guidance which will require management to assess, for each interim and annual period, whether there are conditions or events that raise substantial doubt about an entity's ability to continue as a going concern. Substantial doubt about an entity's ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year after the date the financial statements are issued. When management identifies conditions or events that raise substantial doubt about an entity's ability to continue as a going concern, management is required to disclose information that enables users of the financial statements to understand the principal conditions or events that raised substantial doubt about the entity's ability to continue as a going concern and management's evaluation of the significance of those conditions or events. If substantial doubt about the entity's ability to continue as a going concern has been alleviated as a result of management's plan, the entity should disclose information that allows the users of the financial statements to understand those plans. If the substantial doubt about the entity's ability to continue as a going concern is not alleviated by management's plans, management's plans to mitigate the conditions or events that gave rise to the substantial doubt about the entity's ability to continue as a going concern should be disclosed, as well as a statement that there is substantial doubt the entity's ability to continue as a going concern within one year after the date the financial statements are issued. For all entities, this guidance should be applied prospectively within the annual periods ending after December 15, 2016, and for annual periods and interim periods thereafter. Early adoption is permitted. Talen Energy will adopt this guidance for the annual period ending December 31, 2016. The adoption of this guidance is not expected to have a significant impact. Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity In November 2014, the FASB issued guidance that clarifies how current accounting guidance should be interpreted when evaluating the economic characteristics and risks of a host contract of a hybrid financial instrument issued in the form of a share. This guidance does not change the current criteria for determining whether separation of an embedded derivative feature from a hybrid financial instrument is required. Entities are still required to evaluate whether the economic risks of the embedded derivative feature are clearly and closely related to those of the host contract, among other relevant criteria. An entity should consider the substantive terms and features of the entire hybrid financial instrument, including the embedded derivative feature being evaluated for bifurcation, in evaluating the nature of the host contract to determine whether the host contract is more akin to a debt instrument or more akin to an equity instrument. An entity should assess the relative strength of the debt-like and equity-like terms and features when determining how to weight those terms and features. For public business entities, this guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015 and should be applied using a modified retrospective method for existing hybrid financial instruments issued in the form of a share as of the beginning of the fiscal year the guidance is adopted. Early adoption is permitted. Retrospective application is permitted but not required. Talen Energy will adopt this guidance on January 1, 2016. The adoption of this guidance is not expected to have a significant impact. Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued accounting guidance to simplify the presentation of debt issuance costs by requiring debt issuance costs to be presented on the balance sheet as a direct deduction from the carrying amount of the associated debt liability, consistent with the presentation of debt discounts. Because this guidance did not address the treatment of debt issuance costs related to line-of-credit arrangements, additional guidance was issued in August 2015 stating that an entity may defer and amortize debt issuance costs over the term of a line-of-credit arrangement, regardless of whether there are any related outstanding borrowings. For public business entities, this guidance should be applied retrospectively for financial statements issued for fiscal years beginning after December 15, 2015 and interim periods within those fiscal years. Early adoption is permitted. Talen Energy will adopt this guidance on January 1, 2016. The adoption of this guidance will require Talen Energy to reclassify debt issuance costs from assets to long-term debt, and is not expected to have a significant impact.

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Talen Energy Corporation's obligation to report under the Securities and Exchange Act of 1934, as amended, commenced on May 1, 2015, the date Talen Energy Corporation's Registration Statement on Form S-1 relating to the spinoff transaction was declared effective by the SEC. Talen Energy Supply is a separate registrant and is considered the predecessor of Talen Energy Corporation. Therefore, the financial information prior to June 1, 2015 presented in this Quarterly Report on Form 10-Q for both registrants includes only legacy Talen Energy Supply information. From June 1, 2015, upon completion of the spinoff and acquisition, Talen Energy Corporation's and Talen Energy Supply's consolidated financial information also includes RJS. As such, Talen Energy Corporation's and Talen Energy Supply's consolidated financial information presented in this Quarterly Report on Form 10-Q for the 2015 periods represents three and nine months of legacy Talen Energy Supply information consolidated with three and four months of RJS information, while the 2014 periods represent only legacy Talen Energy Supply information. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X and, therefore, do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation in accordance with GAAP are reflected in the condensed consolidated financial statements. All adjustments are of a normal recurring nature, except as otherwise disclosed. The Balance Sheets at December 31, 2014 are derived from Talen Energy Supply's 2014 audited Balance Sheet. The financial statements and notes thereto should be read in conjunction with the financial statements and notes contained in the 2015 Prospectus. The results of operations for the three and nine months ended September 30, 2015 are not necessarily indicative of the results to be expected for the full year ending December 31, 2015 or other future periods, because results for interim periods can be disproportionately influenced by various factors, developments and seasonal variations. The classification of certain prior period amounts has been changed to conform to the presentation in the September 30, 2015 financial statements. "Income (Loss) from Discontinued Operations (net of income taxes)" for the three and nine months ended September 30, 2015 on the Statement of Income represents the activities of Sapphire, the assets and liabilities of which, at September 30, 2015 , have been classified as "Assets of discontinued operations" and "Liabilities of discontinued operations" on the Balance Sheet, except for Sapphire's heat rate call options and working capital items, which may be retained, and therefore were not included in "Liabilities of discontinued operations" on the Balance Sheet. The Sapphire discontinued operations, discussed herein, excludes the heat rate call options. "Income (Loss) from Discontinued Operations (net of income taxes)" for the three and nine months ended September 30, 2014 on the Statement of Income represents the activities of Talen Montana's hydroelectric generating facilities sold in the fourth quarter of 2014 . The Statements of Cash Flows do not separately report the cash flows of discontinued operations. See Note 7 for additional information.
New Accounting Guidance	Reporting of Discontinued Operations Effective January 1, 2015, Talen Energy prospectively adopted accounting guidance that changes the criteria for determining what should be classified as a discontinued operation and the related presentation and disclosure requirements. A discontinued operation may include a component of an entity or a group of components of an entity, or a business activity. A disposal of a component of an entity or a group of components of an entity is required to be reported in discontinued operations if the disposal represents a strategic shift that has (or will have) a major effect on the entity's operations and financial results when any of the following occurs: (1) the components of an entity or a group of components of an entity meets the criteria to be classified as held for sale, (2) the component of an entity or a group of components of an entity is disposed of by sale, or (3) the component of an entity or a group of components of an entity is disposed of other than by sale (for example, by abandonment or in a distribution to owners in a spinoff). The initial adoption of this guidance did not have a significant impact on Talen Energy but will impact the amounts presented as discontinued operations and will enhance the related disclosure requirements related to future disposals or held for sale classifications. Accounting for Measurement-Period Adjustments Effective September 30, 2015, Talen Energy prospectively adopted accounting guidance that requires an acquirer in a business combination to recognize measurement-period adjustments in the period in which the amounts are determined, including the effect on earnings of any amounts that would have been recorded in prior periods as if the accounting would have been completed at the acquisition date. The acquirer must disclose, by line item, the portion of the adjustment recorded in the current period income statement that would have been recognized in prior periods if the adjustment had been recognized as of the acquisition date. This guidance applies to open measurement periods, and therefore applies to any measurement period adjustments made for the acquisition of RJS Power. See Note 7 for additional information. Accounting for Revenue from Contracts with Customers In May 2014, the FASB issued accounting guidance that establishes a comprehensive new model for the recognition of revenue from contracts with customers. This model is based on the core principle that revenue should be recognized to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance can be applied using either a full retrospective or modified retrospective transition method. In August 2015, the FASB issued guidance that defers the effective date of the standard by one year, which for public business entities, results in initial application of this guidance in annual reporting periods beginning after December 15, 2017 and interim periods within those years. Entities may early adopt the guidance as of the original effective date of the standard, which for public business entities is annual reporting periods beginning after December 15, 2016. Talen Energy expects to adopt this guidance effective January 1, 2018. Talen Energy is currently assessing the impact of adopting this guidance, as well as the transition method it will use. Reporting Uncertainties about an Entity's Ability to Continue as a Going Concern In August 2014, the FASB issued accounting guidance which will require management to assess, for each interim and annual period, whether there are conditions or events that raise substantial doubt about an entity's ability to continue as a going concern. Substantial doubt about an entity's ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year after the date the financial statements are issued. When management identifies conditions or events that raise substantial doubt about an entity's ability to continue as a going concern, management is required to disclose information that enables users of the financial statements to understand the principal conditions or events that raised substantial doubt about the entity's ability to continue as a going concern and management's evaluation of the significance of those conditions or events. If substantial doubt about the entity's ability to continue as a going concern has been alleviated as a result of management's plan, the entity should disclose information that allows the users of the financial statements to understand those plans. If the substantial doubt about the entity's ability to continue as a going concern is not alleviated by management's plans, management's plans to mitigate the conditions or events that gave rise to the substantial doubt about the entity's ability to continue as a going concern should be disclosed, as well as a statement that there is substantial doubt the entity's ability to continue as a going concern within one year after the date the financial statements are issued. For all entities, this guidance should be applied prospectively within the annual periods ending after December 15, 2016, and for annual periods and interim periods thereafter. Early adoption is permitted. Talen Energy will adopt this guidance for the annual period ending December 31, 2016. The adoption of this guidance is not expected to have a significant impact. Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity In November 2014, the FASB issued guidance that clarifies how current accounting guidance should be interpreted when evaluating the economic characteristics and risks of a host contract of a hybrid financial instrument issued in the form of a share. This guidance does not change the current criteria for determining whether separation of an embedded derivative feature from a hybrid financial instrument is required. Entities are still required to evaluate whether the economic risks of the embedded derivative feature are clearly and closely related to those of the host contract, among other relevant criteria. An entity should consider the substantive terms and features of the entire hybrid financial instrument, including the embedded derivative feature being evaluated for bifurcation, in evaluating the nature of the host contract to determine whether the host contract is more akin to a debt instrument or more akin to an equity instrument. An entity should assess the relative strength of the debt-like and equity-like terms and features when determining how to weight those terms and features. For public business entities, this guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015 and should be applied using a modified retrospective method for existing hybrid financial instruments issued in the form of a share as of the beginning of the fiscal year the guidance is adopted. Early adoption is permitted. Retrospective application is permitted but not required. Talen Energy will adopt this guidance on January 1, 2016. The adoption of this guidance is not expected to have a significant impact. Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued accounting guidance to simplify the presentation of debt issuance costs by requiring debt issuance costs to be presented on the balance sheet as a direct deduction from the carrying amount of the associated debt liability, consistent with the presentation of debt discounts. Because this guidance did not address the treatment of debt issuance costs related to line-of-credit arrangements, additional guidance was issued in August 2015 stating that an entity may defer and amortize debt issuance costs over the term of a line-of-credit arrangement, regardless of whether there are any related outstanding borrowings. For public business entities, this guidance should be applied retrospectively for financial statements issued for fiscal years beginning after December 15, 2015 and interim periods within those fiscal years. Early adoption is permitted. Talen Energy will adopt this guidance on January 1, 2016. The adoption of this guidance will require Talen Energy to reclassify debt issuance costs from assets to long-term debt, and is not expected to have a significant impact.
Interest expense allocated to discontinued operations	Represents allocated interest expense based upon the discontinued operations share of the net assets of Talen Energy.
Fair Value Transfer	Transfers between levels are recognized at end-of-reporting-period values.
Master Netting Arrangements	Net derivative positions on the balance sheets are not offset against the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a payable) under master netting arrangements.
Impairment of goodwill and long-lived assets	U.S. GAAP requires that a long-lived asset (or asset group) be tested for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Similarly, a goodwill impairment test is performed annually or more frequently if events or changes in circumstances indicate that more likely than not the carrying amount of a reporting unit may be greater than its fair value. During the second quarter of 2015, due to the impairment of its investment in PPL Energy Supply recorded by PPL (Talen Energy's former parent) at the time of the spinoff, coupled with, and, primarily driven by, Talen Energy Corporation's stock price at the spinoff date, Talen Energy's management concluded that these factors could be indicators of potential impairment with respect to certain long-lived assets and goodwill. After considering additional information, Talen Energy determined that the undiscounted cash flows for potentially affected long-lived assets would not be directly impacted by these factors and therefore concluded that the undiscounted cash flows continued to exceed the carrying value and no further testing of long-lived assets was necessary in the second quarter. Management also performed an interim goodwill impairment assessment as of June 1, 2015, the spinoff and acquisition date. The goodwill impairment analysis is a two-step process. The first step, used to identify potential impairment, is a comparison of the reporting unit's estimated fair value to its carrying value, including goodwill. If the fair value of the reporting unit exceeds its carrying value, applicable goodwill is not considered to be impaired. If the carrying value exceeds the fair value, there is an indication of impairment and the second step is performed to measure the amount of the impairment, if any. The second step requires a company to calculate an implied fair value of goodwill based on a hypothetical purchase price allocation. The East reporting unit, which is equivalent to the East segment continuing operations, failed step one as of June 1, 2015. The step two analysis was not able to be completed by the filing of the second quarter Form 10-Q. As provided for in the applicable accounting guidance, no goodwill impairment charge was recorded based on management's best estimate at that time, which was confirmed when the second quarter analysis was subsequently completed.
Investments	Securities held by Talen Energy's NDT funds and auction rate securities are classified as available-for-sale. Available-for-sale securities are carried on the Balance Sheets at fair value. Unrealized gains and losses on these securities are reported, net of tax, in OCI or are recognized currently in earnings when a decline in fair value is determined to be other-than-temporary. The specific identification method is used to calculate realized gains and losses.

Segment and Related Informati29

Segment and Related Information (Tables)	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Reconciliation of Segments to Consolidated	Financial data for the segments and reconciliation to consolidated results for the periods ended September 30 are: Three Months Nine Months 2015 2014 2015 2014 Income Statement Data Revenues from external customers (a) East $ 1,325 $ 1,601 $ 3,305 $ 1,653 West 94 — 125 — Total $ 1,419 $ 1,601 $ 3,430 $ 1,653 Operating Income (Loss) East $ (230 ) $ 242 $ 132 $ 307 West 24 — 18 — Other (40 ) (53 ) (184 ) (181 ) Total $ (246 ) $ 189 $ (34 ) $ 126 Balance Sheet Data September 30, 2015 December 31, 2014 Assets East $ 11,128 $ 10,468 West 1,066 — Other (b) 60 292 Total Assets $ 12,254 $ 10,760 (a) Includes unrealized gains and losses from derivatives. See Note 14 for additional information. (b) Primarily consists of unallocated items, including cash and PP&E.

Earnings (Loss) Per Share for30

Earnings (Loss) Per Share for Talen Energy Corporation (Tables)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Basic and Diluted EPS Computations	Reconciliations of the amounts of income and shares of Talen Energy Corporation common stock (in thousands) for the periods ended September 30 used in the EPS calculation are: Three Months Nine Months 2015 2014 2015 2014 Income (Numerator) Income (Loss) from continuing operations after income taxes $ (339 ) $ 94 $ (218 ) $ 38 Income (Loss) from discontinued operations (net of income taxes) (62 ) 7 (61 ) 10 Net Income (Loss) $ (401 ) $ 101 $ (279 ) $ 48 Shares of Common Stock (Denominator) Weighted-average shares - Basic EPS 128,509 83,524 103,627 83,524 Weighted-average shares - Diluted EPS 128,509 83,524 103,627 83,524

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income tax provision reconciliation	Selected information regarding Talen Energy's income tax provision for the periods ended September 30 was as follows: Three Months Nine Months 2015 2014 2015 2014 Income (Loss) from Continuing Operations Before Income Taxes $ (300 ) $ 168 $ (169 ) $ 54 Income Taxes $ 39 $ 74 $ 49 $ 16 Effective Tax Rate (13 )% 44 % (29 )% 30 %

Financing Activities (Tables)

Financing Activities (Tables)	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Schedule of Line of Credit Facilities	The amounts borrowed below are recorded as "Short-term debt" on the Balance Sheets. The following credit facility was in place at: September 30, 2015 Expiration Date Capacity Borrowed Letters of Unused Capacity Syndicated Secured Credit Facility (a) June 2020 $ 1,850 $ — $ 334 $ 1,516 (a) The facility includes capacity available for letters of credit and for short-term borrowings. The facility requires Talen Energy Supply to maintain a senior secured debt to adjusted EBITDA ratio (as defined in the agreement) of less than or equal to 4.50 to 1.00 as of the last day of any fiscal quarter. The company pays customary fees on the facility and borrowings bear interest at the company's option at either a defined base rate or LIBOR-based rates, in each case plus an applicable margin.

Acquisitions, Development and33

Acquisitions, Development and Divestitures (Tables)	9 Months Ended
	Sep. 30, 2015
Acquisitions Development And Divestitures [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the preliminary allocation of the purchase price to the fair values of the major classes of assets and liabilities of RJS, all of which represent non-cash activity excluded from the Statement of Cash Flows for the nine months ended September 30, 2015 . Current assets (a) $ 164 Assets of discontinued operations (b) 375 PP&E 1,777 Other intangibles (c) 46 Current liabilities (259 ) Liabilities of discontinued operations (5 ) Long-term debt (1,244 ) Deferred income taxes (266 ) Other noncurrent liabilities (d) (80 ) Net identifiable assets acquired 508 Goodwill (e) 394 Net assets acquired $ 902 (a) Includes gross contractual amount of the accounts receivable acquired of $41 million , which approximates fair value. (b) See Note 13 for information on impairment charges recorded during the third quarter of 2015 related to the Sapphire portfolio. (c) Includes $28 million for a pipeline lease that will be amortized over a 14 year period, and $17 million for an ash site permit that has an amortization period of 10 years. (d) Includes $33 million for "out-of-the-money" coal contracts that will be amortized over the contract term as the coal is consumed. (e) The preliminary allocation above is as of the acquisition date of June 1, 2015. As further discussed in Note 15, goodwill was fully impaired at September 30, 2015, which included the goodwill recognized in the acquisition of RJS Power.
Pro Forma Information	Actual operating revenues and net income of RJS, since the June 1 acquisition, included in Talen Energy's results for the periods ended September 30, 2015 were: Three Months Nine Months Operating Revenues Net Income (Loss) (a) Operating Revenues Net Income (Loss)(a) RJS actual for 2015 $ 237 $ 34 $ 339 $ 48 (a) Includes the operating results of the Sapphire portfolio, which is classified as discontinued operations. Excludes the impact of goodwill and long-lived asset impairments recorded during the three and nine months ended September 30, 2015. See Notes 13 and 15 for information on the impairments recorded. Pro forma information for Talen Energy for the periods ended September 30, as if the acquisition had occurred January 1, 2014, is as follows: Three Months Nine Months Operating Revenues Income (Loss) from Continuing Operations After Tax Operating Revenues Income (Loss) from Continuing Operations After Tax 2015: Pro forma $ 1,420 $ 110 $ 3,723 $ 235 Basic and diluted earnings per share (for Talen Energy Corporation) 0.86 1.83 2014: Pro forma 1,758 79 2,361 47 Basic and diluted earnings per share (for Talen Energy Corporation) 0.61 0.37
Sapphire
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Schedule of Components of Discontinued Operations	Following are the components of discontinued operations, since the June 1 acquisition, on the Statement of Income for the periods ended September 30, 2015 . Three Months Nine Months Operating revenues $ 36 $ 44 Operating expenses 27 34 Impairment (a) 109 109 Income (loss) before income taxes (100 ) (99 ) Income tax expense 38 38 Income (Loss) from Discontinued Operations (net of income taxes) $ (62 ) $ (61 ) (a) See Notes 13 and 15 for additional information on this non-cash charge.
Talen Montana Hydro Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Schedule of Components of Discontinued Operations	Following are the components of discontinued operations on the Statement of Income for the periods ended September 30 , 2014 . Three Months Nine Months Operating revenues $ 33 $ 103 Interest expense (a) 2 6 Income (loss) before income taxes (b) 11 20 Income (Loss) from Discontinued Operations (net of income taxes) (b) 7 10 (a) Represents allocated interest expense based upon the discontinued operations share of the net assets of Talen Energy. (b) Includes an impairment charge related to the Kerr Dam Project. See Note 13 for additional information on this non-cash charge.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Assumptions	The assumptions used in the model were: Risk-free interest rate 2.05 % Expected option life 6 years Expected stock volatility 21.55 %

Defined Benefits (Tables)

Defined Benefits (Tables)	9 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Schedule Of Net Periodic Defined Benefit Costs (Credits)	The following table provides the components of net periodic defined benefit costs for Talen Energy pension plans for the periods ended September 30 , for which the nine months of 2015 includes four months of costs under the newly formed Talen Energy pension plan. The net periodic defined benefit costs for other postretirement benefit plans for the periods ended September 30, 2015 and 2014 were insignificant. Pension Benefits Three Months Nine Months 2015 2014 2015 2014 Service cost $ 12 $ 1 $ 19 $ 4 Interest cost 18 3 28 7 Expected return on plan assets (23 ) (3 ) (37 ) (8 ) Amortization of: Actuarial (gain) loss 6 — 9 1 Net periodic defined benefit costs (credits) $ 13 $ 1 $ 19 $ 4
Allocation of Net Periodic Benefit Costs	The table below provides the costs from defined benefit plans sponsored by PPL Services allocated to Talen Energy Supply based on its participation in those plans prior to the separation on June 1, 2015, which management believes were reasonable at the time. The allocations include costs related to supplemental retirement benefits for executives and other key management employees through unfunded nonqualified retirement plans. The liabilities for these plans were retained by PPL as of the date of the spinoff. Three Months Nine Months 2015 2014 2015 2014 Pension and other postretirement benefits (a) $ — $ 2 $ 18 $ 32 (a) The three and nine months ended September 30, 2014 includes $(5) million and $11 million of termination benefits (credits) related to a one-time voluntary retirement window offered to certain bargaining unit employees upon the ratification of a new union agreement in June 2014. The benefits offered were consistent with the standard separation program benefits for bargaining unit employees.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Guarantees	Talen Energy's exposure and related expiration dates are: Exposure at Expiration Date Indemnifications for sales of assets $ 1,150 2016 - 2025

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2015
Related Party Transactions [Abstract]
Intercompany Support Cost Allocations	Talen Energy Supply was charged, primarily by PPL Services, the following amounts for the periods ended September 30, and believes these amounts were reasonable at the time, including amounts applied to accounts that are further distributed between capital and expense. Three Months Nine Months 2015 2014 2015 2014 $ — $ 49 $ 67 $ 161

Fair Value Measurements and C38

Fair Value Measurements and Credit Concentration (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities Measured on Recurring Basis	The assets and liabilities measured at fair value were: September 30, 2015 December 31, 2014 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 648 $ 648 $ — $ — $ 352 $ 352 $ — $ — Restricted cash and cash equivalents (a) 83 83 — — 193 193 — — Price risk management assets: Energy commodities 802 — 739 63 1,318 6 1,171 141 Total price risk management assets 802 — 739 63 1,318 6 1,171 141 NDT funds: Cash and cash equivalents 13 13 — — 19 19 — — Equity securities U.S. large-cap 581 433 148 — 611 454 157 — U.S. mid/small-cap 84 35 49 — 89 37 52 — Debt securities U.S. Treasury 94 94 — — 99 99 — — U.S. government sponsored agency 7 — 7 — 9 — 9 — Municipality 81 — 81 — 76 — 76 — Investment-grade corporate 49 — 49 — 42 — 42 — Other 4 — 4 — 3 — 3 — Receivables (payables), net — (3 ) 3 — 2 — 2 — Total NDT funds 913 572 341 — 950 609 341 — Auction rate securities (b) 6 — — 6 8 — — 8 Total assets $ 2,452 $ 1,303 $ 1,080 $ 69 $ 2,821 $ 1,160 $ 1,512 $ 149 Liabilities Price risk management liabilities: Energy commodities $ 684 $ — $ 626 $ 58 $ 1,217 $ 5 $ 1,182 $ 30 Total price risk management liabilities $ 684 $ — $ 626 $ 58 $ 1,217 $ 5 $ 1,182 $ 30 (a) Current portion is included in "Restricted cash and cash equivalents" and long-term portion is included in "Other noncurrent assets" on the Balance Sheets. (b) Included in "Other investments" on the Balance Sheets.
Reconciliation of Net Assets and Liabilities Classified as Level 3	A reconciliation of net assets and liabilities classified as Level 3 for the periods ended September 30, 2015 is as follows: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Three Months Nine Months Energy Commodities, net Auction Rate Securities Total Energy Commodities, net Auction Rate Securities Total Balance at beginning of period $ 10 $ 7 $ 17 $ 111 $ 8 $ 119 Total realized/unrealized gains (losses) Included in earnings (7 ) — (7 ) (148 ) — (148 ) Purchases (a) — — — (39 ) — (39 ) Sales — (1 ) (1 ) 65 (2 ) 63 Settlements (9 ) — (9 ) (6 ) — (6 ) Transfers into Level 3 — — — 10 — 10 Transfers out of Level 3 11 — 11 12 — 12 Balance at end of period $ 5 $ 6 $ 11 $ 5 $ 6 $ 11 (a) Positions acquired through the acquisition of RJS Power. A reconciliation of net assets and liabilities classified as Level 3 for the periods ended September 30, 2014 is as follows: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Three Months Nine Months Energy Commodities, net Auction Rate Securities Total Energy Commodities, net Auction Rate Securities Total Balance at beginning of period $ 74 $ 13 $ 87 $ 24 $ 16 $ 40 Total realized/unrealized gains (losses) Included in earnings (84 ) — (84 ) (147 ) — (147 ) Purchases — — — (6 ) — (6 ) Sales 67 (3 ) 64 67 (6 ) 61 Settlements (37 ) — (37 ) 82 — 82 Balance at end of period $ 20 $ 10 $ 30 $ 20 $ 10 $ 30
Significant Unobservable Inputs Used in Fair Value Measurement of Assets and Liabilities Classified as Level 3	The significant unobservable inputs used in and quantitative information about the fair value measurement of assets and liabilities classified as Level 3 are as follows: September 30, 2015 Talen Energy Fair Value, net Asset (Liability) Valuation Technique Significant Unobservable Input(s) Range (Weighted Average) (a) Energy commodities Natural gas contracts (b) $ 31 Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (37%) Power sales contracts (c) (2 ) Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (70%) FTR purchase contracts (d) (1 ) Discounted cash flow Historical settled prices used to model forward prices 100% (100%) Heat rate call options (e) (21 ) Discounted cash flow Proprietary model used to calculate forward prices 100% (100%) CRR purchase contracts (g) (2 ) Discounted cash flow Proprietary model used to calculate forward prices 100% (100%) Auction rate securities (f) 6 Discounted cash flow Modeled from SIFMA Index 52% - 57% (54%) December 31, 2014 Talen Energy Fair Value, net Asset (Liability) Valuation Technique Significant Unobservable Range (Weighted Average) (a) Energy commodities Natural gas contracts (b) $ 59 Discounted cash flow Proprietary model used to calculate forward prices 11% - 100% (52%) Power sales contracts (c) (1 ) Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (59%) FTR purchase contracts (d) 3 Discounted cash flow Historical settled prices used to model forward prices 100% (100%) Heat rate call options (e) 50 Discounted cash flow Proprietary model used to calculate forward prices 23% - 51% (45%) Auction rate securities (f) 8 Discounted cash flow Modeled from SIFMA Index 51% - 69% (63%) (a) The range and weighted average represent the percentage of fair value derived from the unobservable inputs. (b) As the forward price of natural gas increases/(decreases), the fair value of purchase contracts increases/(decreases). As the forward price of natural gas increases/(decreases), the fair value of sales contracts (decreases)/increases. (c) As forward market prices increase/(decrease), the fair value of contracts (decreases)/increases. As volumetric assumptions for contracts in a gain position increase/(decrease), the fair value of contracts increases/(decreases). As volumetric assumptions for contracts in a loss position increase/(decrease), the fair value of the contracts (decreases)/increases. (d) As the forward implied spread increases/(decreases), the fair value of the contracts increases/(decreases). (e) The proprietary model used to calculate fair value incorporates market heat rates, correlations and volatilities. As the market implied heat rate increases/(decreases), the fair value of purchased calls increases/(decreases). As the market implied heat rate increases/(decreases), the fair value of sold calls (decreases)/increases. (f) The model used to calculate fair value incorporates an assumption that the auctions will continue to fail. As the modeled forward rates of the SIFMA Index increase/(decrease), the fair value of the securities increases/(decreases). (g) As the forward implied spread increases/(decreases), the fair value of the contracts increases/(decreases). The significant unobservable inputs used in and the quantitative information about the nonrecurring fair value measurement of assets and liabilities classified as Level 3 are as follows: Fair Value, net Asset (Liability) Valuation Technique Significant Unobservable Input(s) Range (Weighted Average)(a) Kerr Dam Project (March 31, 2014) $ 29 Discounted cash flow Proprietary model used to calculate plant value 38% (38%) Sapphire portfolio and C.P. Crane plant (September 30, 2015) 266 Discounted cash flow Proprietary model used to calculate plant value 100% (100%) (a) The range and weighted average represent the percentage of fair value derived from the unobservable inputs.
Fair Value of Assets and Liabilities Classified as Level 3 Measured on Recurring Basis Included in Earnings	Net gains and losses on assets and liabilities classified as Level 3 and included in earnings for the periods ended September 30 are reported in the Statements of Income as follows: Three Months Energy Commodities, net Wholesale Energy Retail Energy Energy Purchases 2015 2014 2015 2014 2015 2014 Total gains (losses) included in earnings $ 2 $ (102 ) $ (1 ) $ 16 $ (8 ) $ 2 Change in unrealized gains (losses) relating 8 6 12 13 (1 ) 1 Nine Months Energy Commodities, net Wholesale Energy Retail Energy Energy Purchases 2015 2014 2015 2014 2015 2014 Total gains (losses) included in earnings $ (108 ) $ (133 ) $ (33 ) $ (35 ) $ (7 ) $ 21 Change in unrealized gains (losses) relating (31 ) 5 9 (12 ) (5 ) (3 )
Fair Value of Assets and Liabilities Measured on Nonrecurring Basis	The following nonrecurring fair value measurements occurred during the periods ended September 30, 2015 and 2014 resulting in asset impairments: Carrying Amount (a) Fair Value Measurements Using Level 3 (b) Pre-tax Loss (c) Kerr Dam Project (March 31, 2014) $ 47 $ 29 $ 18 Sapphire portfolio and C.P. Crane plant (September 30, 2015) 388 266 122 (a) Represents carrying value before fair value measurement. (b) For the Sapphire portfolio, also reflects estimated cost to sell. (c) The impairments on the Kerr Dam Project and Sapphire portfolio are included in "Income (Loss) from Discontinued Operations (net of income taxes)" on the Statement of Income. The impairment on the C.P. Crane plant is included in "Impairments" on the Statement of Income.
Fair Value of Financial Instruments Not Recorded at Fair Value - Other	The carrying amounts of long-term debt on the Balance Sheets and its estimated fair values are set forth below. The fair value was estimated using an income approach by discounting future cash flows at estimated current cost of funding rates, which incorporates the credit risk of Talen Energy Supply. Long-term debt is classified as Level 2. September 30, 2015 December 31, 2014 Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt $ 4,030 $ 3,717 $ 2,218 $ 2,204

Derivative Instruments and He39

Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Commodity Price Risk (Non-trading) - Economic Activity - Pre-tax Gains (Losses) Associated with Economic Activity	The unrealized gains (losses) for economic activity for the periods ended September 30 were as follows. Three Months Nine Months 2015 2014 2015 2014 Operating Revenues Wholesale energy (a) $ (77 ) $ 299 $ (234 ) $ (581 ) Retail energy (3 ) 2 (25 ) (20 ) Operating Expenses Fuel (3 ) (9 ) 13 (3 ) Energy purchases (a) 130 (217 ) 370 402 (a) In the third quarter of 2015, Talen Energy refined an input used in its valuation technique for certain PJM basis curves as observable inputs became available. This change resulted in the recording of a $30 million net unrealized gain, primarily reflected in "Wholesale energy" revenue on the Statement of Income.
Commodity Volumes - Volumes of Derivative (Sales) Purchase Contracts	At September 30, 2015 , the net volumes of derivative (sales)/purchase contracts used in support of the various strategies discussed above were as follows. Volumes (a) Commodity Unit of Measure 2015 (b) 2016 2017 Thereafter Power MWh (13,407,010 ) (29,872,806 ) (1,202,348 ) (795,983 ) Capacity MW-Month (538 ) (878 ) 6 3 Gas MMBtu 61,373,321 98,156,219 15,586,507 19,636,898 FTRs MW-Month 2,023 2,889 — — Oil Barrels 29,795 60,000 — — CRRs MWh 475,320 1,393,430 538,584 — Emission Allowances Tons 2,253,123 — — — (a) Volumes for option contracts factor in the probability of an option being exercised and may be less than the notional amount of the option. (b) Represents balance of the current year.
Fair Value and Balance Sheet Location of Derivative Instruments	The following table presents the fair value and location of commodity derivative instruments not designated as hedging instruments recorded on the Balance Sheets. September 30, 2015 December 31, 2014 Assets Liabilities Assets Liabilities Current: Price Risk Management Assets/Liabilities: $ 576 $ 506 $ 1,079 $ 1,024 Noncurrent: Price Risk Management Assets/Liabilities: 226 178 239 193 Total derivatives $ 802 $ 684 $ 1,318 $ 1,217
Pre-tax Gain (Loss) on Derivative Instruments Recognized in Income or on the Balance Sheet	The following tables present the pre-tax effect of derivative instruments recognized in income for the periods ended September 30, 2015 . Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Derivative Relationships Location of Gain (Loss) Recognized in Income on Derivative Three Months Nine Months Cash Flow Hedges: Commodity contracts Wholesale energy $ (3 ) $ (3 ) Energy purchases 9 25 Depreciation — 1 Total $ 6 $ 23 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative Three Months Nine Months Commodity contracts Wholesale energy $ 298 $ 328 Retail energy 15 (16 ) Fuel (6 ) (5 ) Energy purchases (183 ) (169 ) Total $ 124 $ 138 The following tables present the pre-tax effect of derivative instruments recognized in income for the periods ended September 30, 2014 . Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Derivative Relationships Location of Gain (Loss) Recognized in Income on Derivative Three Months Nine Months Cash Flow Hedges: Commodity contracts Wholesale energy $ (2 ) $ (1 ) Energy purchases 8 23 Depreciation — 1 Discontinued operations 1 6 Total $ 7 $ 29 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative Three Months Nine Months Commodity contracts Wholesale energy (a) $ 617 $ (2,520 ) Retail energy 18 (34 ) Fuel (8 ) (1 ) Energy purchases (b) (505 ) 1,937 Discontinued operations 2 4 Total $ 124 $ (614 ) (a) The nine month period ended September 30, 2014 includes significant realized and unrealized losses on physical and financial commodity sales contracts due to unusual market and weather volatility. (b) The nine month period ended September 30, 2014 includes significant realized and unrealized gains on physical and financial commodity purchase contracts due to unusual market and weather volatility.
Derivative Positions Eligible for Offset with Related Cash Collateral	The table below summarizes the energy commodities derivative positions presented in the balance sheets where a right of setoff exists under these arrangements and related cash collateral received or pledged. Assets Liabilities Eligible for Offset Eligible for Offset Gross Derivative Instruments Cash Collateral Received Net Gross Derivative Instruments Cash Collateral Pledged Net September 30, 2015 $ 802 $ 567 $ 81 $ 154 $ 684 $ 567 $ 16 $ 101 December 31, 2014 $ 1,318 $ 1,060 $ 10 $ 248 $ 1,217 $ 1,060 $ 58 $ 99
Derivative Positions Eligible for Offset with Related Cash Collateral	The table below summarizes the energy commodities derivative positions presented in the balance sheets where a right of setoff exists under these arrangements and related cash collateral received or pledged. Assets Liabilities Eligible for Offset Eligible for Offset Gross Derivative Instruments Cash Collateral Received Net Gross Derivative Instruments Cash Collateral Pledged Net September 30, 2015 $ 802 $ 567 $ 81 $ 154 $ 684 $ 567 $ 16 $ 101 December 31, 2014 $ 1,318 $ 1,060 $ 10 $ 248 $ 1,217 $ 1,060 $ 58 $ 99

Goodwill and Other Asset Impa40

Goodwill and Other Asset Impairments (Tables)	9 Months Ended
	Sep. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The resulting changes in the carrying amount of Talen Energy's goodwill, all of which was assigned to the East segment, for the nine months ended September 30, 2015 were as follows. Total Balance at December 31, 2014 (a) $ 72 Provisional goodwill recognized during the period (b) 394 Impairment (466 ) Balance at September 30, 2015 (a) $ — (a) There were no accumulated impairment losses related to goodwill at December 31, 2014 and $466 million at September 30, 2015 . (b) Recognized as a result of the acquisition of RJS Power. See Note 7 for additional information.

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2015
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Change in Asset Retirement Obligation	The changes in the carrying amounts of Talen Energy's AROs were as follows. Balance at December 31, 2014 $ 425 Accretion expense 25 Changes in estimate of cash flow or settlement date 21 Obligations assumed in RJS Power acquisition 11 Obligations incurred 3 Obligations settled (2 ) Balance at September 30, 2015 $ 483

Available-for-Sale Securities (

Available-for-Sale Securities (Tables)	9 Months Ended
	Sep. 30, 2015
Available-for-sale Securities [Abstract]
Schedule of Available-for-sale Securities Reconciliation	The following table shows the amortized cost, the gross unrealized gains and losses recorded in AOCI and the fair value of Talen Energy's available-for-sale securities. September 30, 2015 December 31, 2014 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value NDT funds: Cash and cash equivalents $ 13 $ — $ — $ 13 $ 19 $ — $ — $ 19 Equity securities 292 373 — 665 283 417 — 700 Debt securities 227 8 — 235 218 11 — 229 Receivables/payables, net — — — — 2 — — 2 Total NDT funds $ 532 $ 381 $ — $ 913 $ 522 $ 428 $ — $ 950 Auction rate securities $ 6 $ — $ — $ 6 $ 8 $ — $ — $ 8
Investments Classified by Contractual Maturity Date	The following table shows the scheduled maturity dates of debt securities held at September 30, 2015 . Maturity Less Than 1 Year Maturity 1-5 Years Maturity 6-10 Years Maturity in Excess of 10 Years Total Amortized cost $ 11 $ 89 $ 71 $ 62 $ 233 Fair value 11 91 73 66 241
Schedule of Realized Gain (Loss)	The following table shows proceeds from and realized gains and losses on sales of available-for-sale securities for the periods ended September 30 . Three Months Nine Months 2015 2014 2015 2014 Proceeds from sales of NDT securities (a) $ 43 $ 47 $ 143 $ 112 Other proceeds from sales — 3 — 6 Gross realized gains (b) 6 9 19 17 Gross realized losses (b) 7 2 16 6 (a) These proceeds are used to pay income taxes and fees related to managing the trust. Remaining proceeds are reinvested in the trust. (b) Excludes the impact of other-than-temporary impairment charges recognized on the Statements of Income.

Accumulated Other Comprehensi43

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of changes in AOCI by component	The after-tax changes in Talen Energy's AOCI by component for the periods ended September 30 were as follows. Unrealized gains (losses) Defined benefit plans Available- for-sale securities Qualifying derivatives Prior service costs Actuarial gain (loss) Total December 31, 2014 $ 202 $ 63 $ 7 $ (295 ) $ (23 ) Amounts arising during the period (21 ) — (4 ) 46 21 Reclassifications from AOCI (1 ) (14 ) (1 ) 12 (4 ) Net OCI during the period (22 ) (14 ) (5 ) 58 17 September 30, 2015 $ 180 $ 49 $ 2 $ (237 ) $ (6 ) December 31, 2013 $ 173 $ 88 $ (4 ) $ (180 ) $ 77 Amounts arising during the period 18 — — — 18 Reclassifications from AOCI (5 ) (18 ) 2 4 (17 ) Net OCI during the period 13 (18 ) 2 4 1 September 30, 2014 $ 186 $ 70 $ (2 ) $ (176 ) $ 78
Reclassification from AOCI	The following table presents the gains (losses) and related income taxes for reclassifications from Talen Energy's AOCI for the periods ended September 30 . The defined benefit plan components of AOCI are not reflected in their entirety in the statement of income during the periods; rather, they are included in the computation of net periodic defined benefit costs (credits). See Note 9 for additional information. Three Months Nine Months Affected Line Item on the Details about AOCI 2015 2014 2015 2014 Statements of Income Available-for-sale securities $ (1 ) $ 7 $ 3 $ 11 Other Income (Expense) - net Income Taxes — (4 ) (2 ) (6 ) Total After-tax (1 ) 3 1 5 Qualifying derivatives Commodity contracts (3 ) (2 ) (3 ) (1 ) Wholesale energy 9 8 25 23 Energy purchases — 1 — 6 Discontinued operations — — 1 1 Other Total Pre-tax 6 7 23 29 Income Taxes (2 ) (2 ) (9 ) (11 ) Total After-tax 4 5 14 18 Defined benefit plans Prior service costs — (2 ) 1 (4 ) Net actuarial loss (5 ) (1 ) (20 ) (6 ) Total Pre-tax (5 ) (3 ) (19 ) (10 ) Income Taxes 2 1 8 4 Total After-tax (3 ) (2 ) (11 ) (6 ) Total reclassifications during the period $ — $ 6 $ 4 $ 17

Business and Basis of Present44

Business and Basis of Presentation (Details) $ / shares in Units, $ in Millions	3 Months Ended		4 Months Ended	5 Months Ended		9 Months Ended
	Sep. 30, 2015USD ($)$ / shares	Sep. 30, 2014USD ($)$ / shares	Sep. 30, 2015USD ($)	May. 31, 2015USD ($)	[1]	Sep. 30, 2015USD ($)asset_group$ / sharesMW	Sep. 30, 2014USD ($)$ / shares	Dec. 31, 2014USD ($)
Restructuring Cost and Reserve [Line Items]
TSA term of agreement						2 years
Increase (decrease) to retail energy	$ 277	$ 283				$ 831	$ 913
Energy-related businesses	156	189				404	469
Income (Loss) from Continuing Operations Before Income Taxes	(300)	168				(169)	54
Income from continuing operations after income taxes	(339)	94				(218)	38
Net income (loss)	$ (401)	$ 101	$ (311)	$ 32		$ (279)	$ 48
Earnings per share (in dollars per share) | $ / shares	$ (3.12)	$ 1.21				$ (2.69)	$ 0.57
Restatement adjustment | Revenue Adjustment for Affiliate Payable
Restructuring Cost and Reserve [Line Items]
Increase (decrease) to retail energy						$ (7)
Income from continuing operations after income taxes						(4)
Net income (loss)						$ (4)
Earnings per share (in dollars per share) | $ / shares						$ (0.03)
Restatement adjustment | Revenue Adjustment Related to Timing of Revenue Recognition
Restructuring Cost and Reserve [Line Items]
Energy-related businesses		$ 14					$ 17
Energy-related businesses, net of taxes		9					11
Income (Loss) from Continuing Operations Before Income Taxes		14					7
Income from continuing operations after income taxes		9					11
Net income (loss)		$ 9					$ 11
Earnings per share (in dollars per share) | $ / shares		$ 0.11					$ 0.13
PPL Corporation and Topaz Power Management, LP
Restructuring Cost and Reserve [Line Items]
Services provided under TSA	$ 9					$ 14
Spinoff from PPL
Restructuring Cost and Reserve [Line Items]
Restructuring costs						$ 10
Spinoff | Spinoff from PPL
Restructuring Cost and Reserve [Line Items]
Amount of accrued liability for separation benefits								$ 9
Number of asset groups that will be divested | asset_group						1
Number of asset groups proposed to be divested, one of which to be selected | asset_group						2
Spinoff | Spinoff from PPL | Minimum
Restructuring Cost and Reserve [Line Items]
Capacity, in total, to be divested in connection with the spinoff | MW						1,300
Spinoff | Spinoff from PPL | Maximum
Restructuring Cost and Reserve [Line Items]
Capacity, in total, to be divested in connection with the spinoff | MW						1,400
Talen Energy Supply
Restructuring Cost and Reserve [Line Items]
Accelerated stock based compensation and pro-rated stock-based compensation awards						$ 25
Increase (decrease) to retail energy	277	$ 283				831	$ 913
Energy-related businesses	156	189				404	469
Income (Loss) from Continuing Operations Before Income Taxes	(300)	168				(169)	54
Income from continuing operations after income taxes	(339)	94				(218)	38
Net income (loss)	$ (401)	$ 101				$ (279)	$ 48
[1]	Represents Talen Energy Supply's predecessor member's equity balance and activity prior to the June 1, 2015 spinoff transaction.

Segment and Related Informati45

Segment and Related Information (Narrative) (Details) - segment	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting [Abstract]
Number of segments	2	1

Segment and Related Informati46

Segment and Related Information - Income Statement Data (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues from external customers		$ 1,419	$ 1,601	$ 3,430	$ 1,653
Operating income (loss)		(246)	189	(34)	126
Operating Segments | East
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues from external customers	[1]	1,325	1,601	3,305	1,653
Operating income (loss)		(230)	242	132	307
Operating Segments | West
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues from external customers	[1]	94	0	125	0
Operating income (loss)		24	0	18	0
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating income (loss)		$ (40)	$ (53)	$ (184)	$ (181)
[1]	Includes unrealized gains and losses from derivatives. See Note 14 for additional information.

Segment and Related Informati47

Segment and Related Information - Balance Sheet Data (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		$ 12,254	$ 10,760
Operating Segments | East
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		11,128	10,468
Operating Segments | West
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		1,066	0
Other
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	[1]	$ 60	$ 292
[1]	Primarily consists of unallocated items, including cash and PP&E.

Earnings (Loss) Per Share for48

Earnings (Loss) Per Share for Talen Energy Corporation (Details) - USD ($) $ in Millions	Jun. 01, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	May. 31, 2015	[1]	Sep. 30, 2015		Sep. 30, 2014
Income (Numerator)
Income (Loss) from continuing operations after income taxes		$ (339)	$ 94				$ (218)		$ 38
Income (Loss) from discontinued operations (net of income taxes)		(62)	7				(61)		10
Net Income (Loss)		$ (401)	$ 101	$ (311)	$ 32		$ (279)		$ 48
Shares of Common Stock (Denominator)
Weighted-average shares - Basic EPS (in shares)		128,509,000	83,524,000				103,627,000		83,524,000
Weighted-average shares - Diluted EPS (in shares)		128,509,000	83,524,000				103,627,000		83,524,000
Shares Issued (Numeric) [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)		1,263,000					525,000
Common Stock
Schedule of Capitalization, Equity [Line Items]
Stock issuance (shares)	128,499,023
Common stock shares issued to PPL shareholders	83,524,365						83,524,000	[2]
Common stock issued for acquisition of RJS Power, shares	44,974,658						44,975,000	[2]
[1]	Represents Talen Energy Supply's predecessor member's equity balance and activity prior to the June 1, 2015 spinoff transaction.
[2]	Shares in thousands. Each share entitles the holder to one vote on any questions presented at any stockholders' meeting.

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Tax Contingency [Line Items]
Income (Loss) from Continuing Operations Before Income Taxes	$ (300)	$ 168	$ (169)	$ 54
Income Taxes	$ 39	$ 74	$ 49	$ 16
Effective Tax Rate	(13.00%)	44.00%	(29.00%)	30.00%
Annualized effective tax rate			30.76%	36.93%
State deferred taxes			$ 17
IRS
Income Tax Contingency [Line Items]
Tax benefit recorded for previously unrecognized tax benefits			$ 12

Financing Activities (Details)

Financing Activities (Details)		1 Months Ended			9 Months Ended
		Oct. 31, 2015USD ($)	Sep. 30, 2015USD ($)shares	May. 31, 2015USD ($)	Sep. 30, 2015USD ($)shares	Sep. 30, 2014USD ($)	Nov. 02, 2015USD ($)	Aug. 31, 2015	Jul. 31, 2015	Jun. 30, 2015USD ($)	Jun. 01, 2015USD ($)
Credit Arrangments and Short-term Debt
Unamortized fees included in interest expense					$ 12,000,000
Long Term Debt
Total aggregate consideration paid to repurchase debt					$ 33,000,000	$ 308,000,000
Preferred Stock
Preferred stock, shares authorized (in shares) | shares			100,000,000		100,000,000
Preferred stock, shares issued (in shares) | shares			0		0
Preferred stock, shares outstanding (in shares) | shares			0		0
RJS Power
Long Term Debt
Long term debt assumed											$ 1,244,000,000
Exempt Facilities Revenue Refunding Bonds
Long Term Debt
Debt instrument, face amount			$ 231,000,000		$ 231,000,000
Interest rate								3.00%
Term Loan and Revolving Credit Facility | MACH Gen. LLC | Subsequent event
Long Term Debt
Debt outstanding							$ 578,000,000
Term Loan | MACH Gen. LLC | Subsequent event
Credit Arrangments and Short-term Debt
Weighted average interest rate							6.21%
Long Term Debt
Debt outstanding							$ 475,000,000
Series 2009A Bonds | Exempt Facilities Revenue Refunding Bonds
Long Term Debt
Debt instrument, face amount			$ 100,000,000		$ 100,000,000
Interest rate			6.40%		6.40%
Series 2009B and 2009C Bonds | Exempt Facilities Revenue Refunding Bonds
Long Term Debt
Debt instrument, face amount			$ 131,000,000		$ 131,000,000
Interest rate			5.00%		5.00%
Fixed interest rate period until mandatory repurchase and optional remarketing			5 years
Talen Energy Supply
Long Term Debt
Total aggregate consideration paid to repurchase debt					$ 33,000,000	$ 308,000,000
Talen Energy Supply | Redeemable Senior Unsecured Notes due 2025 | Unsecured Debt
Long Term Debt
Debt instrument, face amount				$ 600,000,000
Interest rate				6.50%
Proceeds from debt, net				$ 591,000,000
Talen Energy Supply | Senior Notes due 2019 | Senior Notes
Long Term Debt
Interest rate									4.625%
Talen Energy Supply | Senior Notes due 2019 | Senior Notes | RJS Power
Long Term Debt
Interest rate										5.125%
Long term debt assumed										$ 1,250,000,000
Talen Energy Supply | Reset Put Securities due 2035 | REset Put Securities | Subsequent event
Long Term Debt
Debt instrument, face amount		$ 300,000,000
Interest rate		5.70%
Total aggregate consideration paid to repurchase debt		$ 434,000,000
Principal amount repurchased		300,000,000
Remarketing option value paid		134,000,000
Talen Energy Supply | On or prior to June 1, 2020 | Redeemable Senior Unsecured Notes due 2025 | Unsecured Debt
Long Term Debt
Redemption price percentage				100.00%
Talen Energy Supply | On or prior to June 1, 2018 | Redeemable Senior Unsecured Notes due 2025 | Unsecured Debt
Long Term Debt
Redemption price percentage				106.50%
Redemption price, percentage of principal amount that may be redeemed				35.00%
Syndicated Secured Credit Facility
Credit Arrangments and Short-term Debt
Expiration Date	[1]				Jun. 30, 2020
Capacity	[1]		$ 1,850,000,000		$ 1,850,000,000
Borrowed	[1]		0		0
Letters of Credit Issued	[1]		334,000,000		334,000,000
Unused Capacity	[1]		$ 1,516,000,000		$ 1,516,000,000
Covenant, ratio of secured debt to adjusted EBITDA			4.50		4.50
Syndicated Secured Credit Facility | Talen Energy Supply
Credit Arrangments and Short-term Debt
Carrying value of property subject to lien to support facility			$ 7,000,000,000		$ 7,000,000,000
Syndicated Secured Credit Facility | Talen Energy Supply | Subsequent event
Credit Arrangments and Short-term Debt
Borrowed		550,000,000
Amount borrowed under facility		$ 400,000,000
Weighted average interest rate		2.44%
Facility Agreement | Talen Energy Supply
Credit Arrangments and Short-term Debt
Expiration Date					Jun. 30, 2017
Potential maximum Facility Agreement capacity			500,000,000		$ 500,000,000
Secured Trading Facility | Talen Energy Supply
Credit Arrangments and Short-term Debt
Expiration Date					Nov. 3, 2019
Secured energy marketing and trading facility capacity			$ 800,000,000		$ 800,000,000
Facility term					5 years
Revolving Credit Facility | MACH Gen. LLC | Subsequent event
Credit Arrangments and Short-term Debt
Capacity							160,000,000
Borrowed							$ 103,000,000
Weighted average interest rate							4.98%
[1]	The facility includes capacity available for letters of credit and for short-term borrowings. The facility requires Talen Energy Supply to maintain a senior secured debt to adjusted EBITDA ratio (as defined in the agreement) of less than or equal to 4.50 to 1.00 as of the last day of any fiscal quarter. The company pays customary fees on the facility and borrowings bear interest at the company's option at either a defined base rate or LIBOR-based rates, in each case plus an applicable margin.

Acquisitions, Development and51

Acquisitions, Development and Divestitures (Acquisitions) (Details) $ / shares in Units, $ in Millions		Nov. 02, 2015USD ($)MW	Jun. 01, 2015USD ($)shares	Sep. 30, 2015USD ($)$ / shares	Sep. 30, 2014USD ($)$ / shares	Sep. 30, 2015USD ($)$ / shares	Sep. 30, 2014USD ($)$ / shares	Dec. 31, 2014USD ($)
Preliminary Allocation of the Purchase Price
Goodwill				$ 0		$ 0		$ 72
MACH Gen. LLC | Subsequent event
Business Acquisition [Line Items]
Cash consideration		$ 603
Generating capacity (in MW) | MW		2,500
RJS Power
Business Acquisition [Line Items]
Total consideration			$ 902
Preliminary Allocation of the Purchase Price
Current assets	[1]		164
Assets of discontinued operations (b)	[2]		375
PP&E			1,777
Other intangibles	[3]		46
Current liabilities			(259)
Liabilities of discontinued operations			(5)
Long-term debt			(1,244)
Deferred income taxes			(266)
Other noncurrent liabilities	[4]		(80)
Net identifiable assets acquired			508
Goodwill	[5]		394
Net assets acquired			902
Accounts receivable acquired			41
Out-of-the-money coal contracts			33
Reduction in goodwill from valuation adjustments				4
Pro Forma Information
Actual operating revenue				237		339
Actual net income	[6]			34		48
Pro forma operating revenues				1,420	$ 1,758	3,723	$ 2,361
Pro forma income (loss) after tax from continuing operations				$ 110	$ 79	$ 235	$ 47
Pro Forma earnings per share, basic (in dollars per share) | $ / shares				$ 0.86	$ 0.61	$ 1.83	$ 0.37
Pro Forma earnings per share, diluted (in dollars per share) | $ / shares				$ 0.87	$ 0.59	$ 1.84	$ 0.34
Nonrecurring acquisition, integration and other costs						$ 6
RJS Power | Pipeline lease
Preliminary Allocation of the Purchase Price
Other intangibles			$ 28
Amortization period			14 years
RJS Power | Ash site permit
Preliminary Allocation of the Purchase Price
Other intangibles			$ 17
Amortization period			10 years
RJS Power | Common Stock
Business Acquisition [Line Items]
Shares issued in acquisition (in shares) | shares			44,974,658
[1]	Includes gross contractual amount of the accounts receivable acquired of $41 million, which approximates fair value.
[2]	See Note 13 for information on impairment charges recorded during the third quarter of 2015 related to the Sapphire portfolio.
[3]	Includes $28 million for a pipeline lease that will be amortized over a 14 year period, and $17 million for an ash site permit that has an amortization period of 10 years.
[4]	Includes $33 million for "out-of-the-money" coal contracts that will be amortized over the contract term as the coal is consumed.
[5]	The preliminary allocation above is as of the acquisition date of June 1, 2015. As further discussed in Note 15, goodwill was fully impaired at September 30, 2015, which included the goodwill recognized in the acquisition of RJS Power.
[6]	Includes the operating results of the Sapphire portfolio, which is classified as discontinued operations. Excludes the impact of goodwill and long-lived asset impairments recorded during the three and nine months ended September 30, 2015. See Notes 13 and 15 for information on the impairments recorded.

Acquisitions, Development and52

Acquisitions, Development and Divestitures (Anticipated Divestitures Discontinued Operations) (Details) $ in Millions		1 Months Ended	3 Months Ended			9 Months Ended
		Nov. 30, 2014USD ($)facilityMW	Mar. 31, 2016USD ($)MW	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)
Components of Discontinued Operations
Income (Loss) from Discontinued Operations (net of income taxes)				$ (62)	$ 7	$ (61)	$ 10
Holtwood and Lake Wallenpaupack Hydroelectric Projects | Forecast | Disposal Group Held for Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase price of disposal group			$ 860
Capacity of facility sold | MW			308
Talen Ironwood Holdings, LLC | Forecast | Disposal Group Held for Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase price of disposal group			$ 654
Repayments of indebtedness			$ 41
Capacity of facility sold | MW			660
C.P. Crane, LLC | Forecast | Disposal Group Held for Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Capacity of facility sold | MW			402
Sapphire
Components of Discontinued Operations
Operating revenues				36		44
Operating expenses				27		34
Impairment	[1]			109		109
Income (loss) before income taxes				(100)		(99)
Income tax expense				38		38
Income (Loss) from Discontinued Operations (net of income taxes)				$ (62)		$ (61)
Talen Montana Hydro Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Capacity of facility sold | MW		633
Agreed upon sales price for disposal of hydroelectric facilities owned by PPL Montana		$ 900
Number of hydroelectric facilities owned by PPL Montana to be sold | facility		11
Components of Discontinued Operations
Operating revenues					33		103
Interest expense	[2]				2		6
Income (loss) before income taxes	[3]				11		20
Income (Loss) from Discontinued Operations (net of income taxes)	[3]				$ 7		$ 10
[1]	See Notes 13 and 15 for additional information on this non-cash charge.
[2]	Represents allocated interest expense based upon the discontinued operations share of the net assets of Talen Energy.
[3]	Includes an impairment charge related to the Kerr Dam Project. See Note 13 for additional information on this non-cash charge.

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	5,630,000	5,630,000
Compensation Expense
Compensation expense		$ 18
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	2,000,000	2,000,000
Vesting period		3 years
Period after grant date		1 year
Expiration period		10 years
Options granted in period (in shares)		991,101
Grant date fair value (in dollars per share)		$ 4.91
Assumptions Used
Risk-free interest rate		2.05%
Expected option life		6 years
Expected stock volatility		21.55%
Compensation Expense
Outstanding shares (in shares)			2,745,016
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Units granted in period (in shares)		261,877
Grant date fair value (in dollars per share)		$ 18.86
Restricted stock and restricted stock units
Compensation Expense
Unvested shares (in shares)			1,457,900
Performance units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted in period (in shares)		158,900
Grant date fair value (in dollars per share)		$ 21.17
Performance period		3 years
Maximum target award percentage		200.00%
Assumptions Used
Expected stock volatility		31.80%
Compensation Expense
Unvested shares (in shares)			291,492
Restricted stock units, performance units and stock options
Compensation Expense
Compensation expense	$ 3

Defined Benefits (Details)

Defined Benefits (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 01, 2015
Defined Benefit Plan Disclosure [Line Items]
Unfunded status of plan						$ 235
Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 12	$ 1	$ 19	$ 4
Interest cost		18	3	28	7
Expected return on plan assets		(23)	(3)	(37)	(8)
Amortization of:
Actuarial (gain) loss		6	0	9	1
Net periodic defined benefit costs (credits)		13	1	19	4
Supplemental Retirement Plan
Net Periodic Defined Benefit Costs Allocated to Subsidiary by Sponsor (Numeric) [Abstract]
Severance compensation					6
Talen Energy Supply | Supplemental Retirement Plan
Net Periodic Defined Benefit Costs Allocated to Subsidiary by Sponsor (Numeric) [Abstract]
Costs allocated to subsidiary by plan sponsors	[1]	$ 0	2	$ 18	32
Termination benefits			$ (5)		$ 11
[1]	The three and nine months ended September 30, 2014 includes $(5) million and $11 million of termination benefits (credits) related to a one-time voluntary retirement window offered to certain bargaining unit employees upon the ratification of a new union agreement in June 2014. The benefits offered were consistent with the standard separation program benefits for bargaining unit employees.

Commitments and Contingencies55

Commitments and Contingencies (Energy Purchase Commitments) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Fuel | Loss on Long-term Purchase Contracts
Loss Contingencies [Line Items]
Coal contract modification charges	$ 41	$ 41

Commitments and Contingencies56

Commitments and Contingencies (Legal Matters) (Details)	1 Months Ended							9 Months Ended
	Apr. 30, 2015project	Aug. 31, 2014project	May. 31, 2014project	Jul. 31, 2013project	Mar. 31, 2013USD ($)claim	Jul. 31, 2012USD ($)plaintiff	Apr. 30, 2012utility	Sep. 30, 2015USD ($)
Legal Matters - Sierra Club Litigation (Numeric) [Abstract]
Number of separate claims included in the complaint against PPL Montana | claim					39
Average requested amount, per day per violation, of injunctive relief and civil penalties					$ 36,000
Amount of civil penalties to be used for beneficial mitigation projects					$ 100,000
Estimated number of post-2000 projects alleged not to be in compliance with the Clean Air Act | project				40
Number of plant projects that had claims dismissed under alleged Clean Air Act violations | project			3
Number of plant projects included in a second amended complaint under alleged Clean Air Act violations | project		8
Number of plant projects with remaining claims to be pursued by plaintiffs | project	4
Regulatory Issues - Maryland Capacity Order (Numeric) [Abstract]
Number electric utilities ordered to enter into long term contracts | utility							3
Regulatory Issues - Electric - Reliability Standards (Numeric) [Abstract]
Maximum per day penalties for reliability violations								$ 1,000,000
Pacific Northwest Markets
Regulatory Issues - Pacific Northwest Markets (Numeric) [Abstract]
Number of parties claiming refunds | plaintiff						2
Claim sought						$ 23,000,000
Remaining claim outstanding								$ 50,000,000
Settled litigation | Pacific Northwest Markets
Regulatory Issues - Pacific Northwest Markets (Numeric) [Abstract]
Number of parties claiming refunds | plaintiff						1
Settlement amount reached with one of the parties						$ 75,000

Commitments and Contingencies57

Commitments and Contingencies (Environmental Matters and Other) (Details)	9 Months Ended
	Sep. 30, 2015USD ($)phasecategory
Environmental Matters - Domestic - Air - Cross State Air Pollution Rule (Numeric) [Abstract]
Number of phases CSAPR will be implemented | phase	2
Environmental Matters - Domestic - Water/Waste - Coal Combustion Residuals (CCRs) [Abstract]
Minimum range in years to complete closure requirements for CCRs under certain events	3 years
Maximum range in years to complete closure requirements for CCRs under certain events	10 years
Increase to existing AROs	$ 36,000,000
Environmental Matters - Domestic - Water/Waste - Seepages and Groundwater Infiltration - Pennsylvania, Montana (Numeric) [Abstract]
Period for PPL Montana to provide financial assurance to Montana Department of Environmental Quality (in years)	5 years
Environmental Matters - Waters of the United States (WOTUS) [Abstract]
Number of categories identified | category	6
Number of categories identified to be determined on case-by-case basis | category	2
Other - Nuclear Insurance (Numeric) [Abstract]
Maximum public liability for claims resulting an incident at nuclear station	$ 13,300,000,000
Maximum amount that could be assessed resulting from an incident at nuclear station	255,000,000
Maximum amount payable per year resulting from an incident at nuclear station	38,000,000
Maximum amount of insured property damage losses at nuclear station	2,000,000,000
Maximum assessment for retroactive premiums for nuclear outage insurance coverage	$ 55,000,000
Minimum
Environmental Matters - Domestic - Air - Mercury and Air Toxics Standards (Numeric) [Abstract]
Possible period of extension to comply with final mercury and air toxics standards	1 year
Maximum
Environmental Matters - Domestic - Air - Mercury and Air Toxics Standards (Numeric) [Abstract]
Possible period of extension to comply with final mercury and air toxics standards	2 years

Commitments and Contingencies58

Commitments and Contingencies (Guarantees and Other Assurances) (Details) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Guarantor Obligations [Line Items]
Recorded liability for all guarantees	$ 0	$ 13,000,000
Maximum aggregate coverage bodily injury and property damage	100,000,000
Indemnification Agreement | Indemnifications for sales of assets
Guarantor Obligations [Line Items]
Maximum exposure	$ 1,150,000,000

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Trailstone NA Logistic LLC | Costs for gas purchases
Related Party Transaction [Line Items]
Amount of related party transaction	$ 26		$ 32
Talen Energy Marketing | PPL Electric
Related Party Transaction [Line Items]
Credit exposure with affiliate under a Master Supply Agreement		$ 77	146	$ 261
Talen Energy Supply | PPL Services
Related Party Transaction [Line Items]
Support cost allocations from subsidiary of parent to registrant	0	$ 49	67	$ 161
Talen Energy Supply | Topaz Power Management, LP | Transition Services Agreement
Related Party Transaction [Line Items]
Expenses from transaction with related party	$ 4		$ 5

Fair Value Measurements and C60

Fair Value Measurements and Credit Concentration (Assets and Liabilities Measured on Recurring Basis Table) (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Price risk management assets:
Gross		$ 802	$ 1,318
Price risk management liabilities:
Gross		684	1,217
Recurring
Assets
Cash and cash equivalents		648	352
Restricted cash and cash equivalents	[1]	83	193
Price risk management assets:
Gross		802	1,318
NDT funds		913	950
Total assets		2,452	2,821
Price risk management liabilities:
Gross		684	1,217
Recurring | Cash and cash equivalents
Price risk management assets:
NDT funds		13	19
Recurring | U.S. large-cap
Price risk management assets:
NDT funds		581	611
Recurring | U.S. mid/small-cap
Price risk management assets:
NDT funds		84	89
Recurring | U.S. Treasury
Price risk management assets:
NDT funds		94	99
Recurring | U.S. government sponsored agency
Price risk management assets:
NDT funds		7	9
Recurring | Municipality
Price risk management assets:
NDT funds		81	76
Recurring | Investment-grade corporate
Price risk management assets:
NDT funds		49	42
Recurring | Other
Price risk management assets:
NDT funds		4	3
Recurring | Receivables/payables, net
Price risk management assets:
NDT funds		0	2
Recurring | Auction Rate Securities
Price risk management assets:
Auction rate securities	[2]	6	8
Recurring | Level 1
Assets
Cash and cash equivalents		648	352
Restricted cash and cash equivalents	[1]	83	193
Price risk management assets:
Gross		0	6
NDT funds		572	609
Total assets		1,303	1,160
Price risk management liabilities:
Gross		0	5
Recurring | Level 1 | Cash and cash equivalents
Price risk management assets:
NDT funds		13	19
Recurring | Level 1 | U.S. large-cap
Price risk management assets:
NDT funds		433	454
Recurring | Level 1 | U.S. mid/small-cap
Price risk management assets:
NDT funds		35	37
Recurring | Level 1 | U.S. Treasury
Price risk management assets:
NDT funds		94	99
Recurring | Level 1 | Receivables/payables, net
Price risk management assets:
NDT funds		(3)	0
Recurring | Level 2
Price risk management assets:
Gross		739	1,171
NDT funds		341	341
Total assets		1,080	1,512
Price risk management liabilities:
Gross		626	1,182
Recurring | Level 2 | U.S. large-cap
Price risk management assets:
NDT funds		148	157
Recurring | Level 2 | U.S. mid/small-cap
Price risk management assets:
NDT funds		49	52
Recurring | Level 2 | U.S. government sponsored agency
Price risk management assets:
NDT funds		7	9
Recurring | Level 2 | Municipality
Price risk management assets:
NDT funds		81	76
Recurring | Level 2 | Investment-grade corporate
Price risk management assets:
NDT funds		49	42
Recurring | Level 2 | Other
Price risk management assets:
NDT funds		4	3
Recurring | Level 2 | Receivables/payables, net
Price risk management assets:
NDT funds		3	2
Recurring | Level 3
Price risk management assets:
Gross		63	141
Total assets		69	149
Price risk management liabilities:
Gross		58	30
Recurring | Level 3 | Auction Rate Securities
Price risk management assets:
Auction rate securities	[2]	6	8
Energy Commodities, net | Recurring
Price risk management assets:
Gross		802	1,318
Price risk management liabilities:
Gross		684	1,217
Energy Commodities, net | Recurring | Level 1
Price risk management assets:
Gross		0	6
Price risk management liabilities:
Gross		0	5
Energy Commodities, net | Recurring | Level 2
Price risk management assets:
Gross		739	1,171
Price risk management liabilities:
Gross		626	1,182
Energy Commodities, net | Recurring | Level 3
Price risk management assets:
Gross		63	141
Price risk management liabilities:
Gross		$ 58	$ 30
[1]	Current portion is included in "Restricted cash and cash equivalents" and long-term portion is included in "Other noncurrent assets" on the Balance Sheets.
[2]	Included in "Other investments" on the Balance Sheets.

Fair Value Measurements and C61

Fair Value Measurements and Credit Concentration (Net Asset and Liability Measured on Recurring Basis Level 3 Unobservable Inputs Reconciliation Rollforward) (Details) - Level 3 - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014
Reconciliation of Total
Balance at beginning of period	$ 17	$ 87	$ 119		$ 40
Total realized/unrealized gains (losses) included in earnings	(7)	(84)	(148)		(147)
Purchases	0	0	(39)	[1]	(6)
Sales	(1)	64	63		61
Settlements	(9)	(37)	(6)		82
Transfers into Level 3	0		10
Transfers out of Level 3	11		12
Balance at end of period	11	30	11		30
Auction Rate Securities
Reconciliation of Auction Rate Securities
Balance at beginning of period	7	13	8		16
Sales	(1)	(3)	(2)		(6)
Balance at end of period	6	10	6		10
Energy Commodities, net
Reconciliation of Energy Commodities, net
Balance at beginning of period	10	74	111		24
Total realized/unrealized gains (losses) included in earnings	(7)	(84)	(148)		(147)
Purchases	0	0	(39)	[1]	(6)
Sales	0	67	65		67
Settlements	(9)	(37)	(6)		82
Transfers into Level 3	0		10
Transfers out of Level 3	11		12
Balance at end of period	$ 5	$ 20	$ 5		$ 20
[1]	Positions acquired through the acquisition of RJS Power.

Fair Value Measurements and C62

Fair Value Measurements and Credit Concentration (Net Assets and Liabilities Measured on Recurring Basis Level 3 Significant Unobservable Inputs) (Details) - Recurring - Level 3 - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Auction Rate Securities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of net asset and (liability)	[1]	$ 6	$ 8
Auction Rate Securities | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	[2]	52.00%	51.00%
Auction Rate Securities | Discounted Cash Flow | Maximum
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	[2]	57.00%	69.00%
Auction Rate Securities | Discounted Cash Flow | Weighted Average
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	[2]	54.00%	63.00%
Natural gas contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, fair value, net	[3]	$ 31	$ 59
Natural gas contracts | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	10.00%	11.00%
Natural gas contracts | Discounted Cash Flow | Maximum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%	100.00%
Natural gas contracts | Discounted Cash Flow | Weighted Average
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	37.00%	52.00%
Power sales contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, fair value, net	[4]	$ (2)	$ (1)
Power sales contracts | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	10.00%	10.00%
Power sales contracts | Discounted Cash Flow | Maximum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%	100.00%
Power sales contracts | Discounted Cash Flow | Weighted Average
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	70.00%	59.00%
FTR purchase contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, fair value, net	[5]	$ (1)	$ 3
FTR purchase contracts | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Historical settled prices used to model forward prices	[2]	100.00%	100.00%
FTR purchase contracts | Discounted Cash Flow | Maximum
Fair Value Inputs [Abstract]
Historical settled prices used to model forward prices	[2]	100.00%	100.00%
FTR purchase contracts | Discounted Cash Flow | Weighted Average
Fair Value Inputs [Abstract]
Historical settled prices used to model forward prices	[2]	100.00%	100.00%
Heat rate call options
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, fair value, net	[6]	$ (21)	$ 50
Heat rate call options | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%	23.00%
Heat rate call options | Discounted Cash Flow | Maximum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%	51.00%
Heat rate call options | Discounted Cash Flow | Weighted Average
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%	45.00%
CRR purchase contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, fair value, net	[7]	$ (2)
CRR purchase contracts | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%
CRR purchase contracts | Discounted Cash Flow | Maximum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%
CRR purchase contracts | Discounted Cash Flow | Weighted Average
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%
[1]	The model used to calculate fair value incorporates an assumption that the auctions will continue to fail. As the modeled forward rates of the SIFMA Index increase/(decrease), the fair value of the securities increases/(decreases).
[2]	The range and weighted average represent the percentage of fair value derived from the unobservable inputs.
[3]	As the forward price of natural gas increases/(decreases), the fair value of purchase contracts increases/(decreases). As the forward price of natural gas increases/(decreases), the fair value of sales contracts (decreases)/increases.
[4]	As forward market prices increase/(decrease), the fair value of contracts (decreases)/increases. As volumetric assumptions for contracts in a gain position increase/(decrease), the fair value of contracts increases/(decreases). As volumetric assumptions for contracts in a loss position increase/(decrease), the fair value of the contracts (decreases)/increases.
[5]	As the forward implied spread increases/(decreases), the fair value of the contracts increases/(decreases).
[6]	The proprietary model used to calculate fair value incorporates market heat rates, correlations and volatilities. As the market implied heat rate increases/(decreases), the fair value of purchased calls increases/(decreases). As the market implied heat rate increases/(decreases), the fair value of sold calls (decreases)/increases.
[7]	As the forward implied spread increases/(decreases), the fair value of the contracts increases/(decreases).

Fair Value Measurements and C63

Fair Value Measurements and Credit Concentration (Net Asset and Liability Measured on Recurring Basis Level 3 Gain Loss Included in Earnings and Other Recurring Numeric Data) (Details) - Level 3 - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	$ (7)	$ (84)	$ (148)	$ (147)
Recurring | Energy Commodities, Net | Wholesale energy
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	2	(102)	(108)	(133)
Change in unrealized gains (losses) relating to positions still held at the reporting date	8	6	(31)	5
Recurring | Energy Commodities, Net | Retail Energy
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(1)	16	(33)	(35)
Change in unrealized gains (losses) relating to positions still held at the reporting date	12	13	9	(12)
Recurring | Energy Commodities, Net | Energy purchases
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(8)	2	(7)	21
Change in unrealized gains (losses) relating to positions still held at the reporting date	$ (1)	$ 1	$ (5)	$ (3)

Fair Value Measurements and C64

Fair Value Measurements and Credit Concentration (Nonrecurring Fair Value Measurements) (Details) - Nonrecurring - USD ($) $ in Millions		Sep. 30, 2015	Mar. 31, 2014	Mar. 31, 2014	Sep. 30, 2015	Sep. 30, 2014
Kerr Dam Project
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Pre-tax loss				$ 18		$ 18	[1]
Sapphire Portfolio and C.P. Crane Plant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Pre-tax loss	[1]				$ 122
Carrying Amount | Kerr Dam Project
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Nonrecurring measurement asset value	[2]		$ 47	47
Carrying Amount | Sapphire Portfolio and C.P. Crane Plant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Nonrecurring measurement asset value	[2]	$ 388			388
Level 3 | Kerr Dam Project
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Nonrecurring measurement asset value						$ 29
Fair value of net asset and (liability)			$ 29	$ 29
Level 3 | Sapphire Portfolio and C.P. Crane Plant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Nonrecurring measurement asset value	[3]	266			266
Fair value of net asset and (liability)		$ 266			$ 266
Discounted Cash Flow | Minimum | Level 3 | Kerr Dam Project
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Proprietary model used to calculate plant value	[4]		38.00%
Discounted Cash Flow | Minimum | Level 3 | Sapphire Portfolio and C.P. Crane Plant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Proprietary model used to calculate plant value	[4]	100.00%
Discounted Cash Flow | Maximum | Level 3 | Kerr Dam Project
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Proprietary model used to calculate plant value	[4]		38.00%
Discounted Cash Flow | Maximum | Level 3 | Sapphire Portfolio and C.P. Crane Plant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Proprietary model used to calculate plant value	[4]	100.00%
Discounted Cash Flow | Weighted Average | Level 3 | Kerr Dam Project
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Proprietary model used to calculate plant value	[4]		38.00%
Discounted Cash Flow | Weighted Average | Level 3 | Sapphire Portfolio and C.P. Crane Plant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Proprietary model used to calculate plant value	[4]	100.00%
[1]	The impairments on the Kerr Dam Project and Sapphire portfolio are included in "Income (Loss) from Discontinued Operations (net of income taxes)" on the Statement of Income. The impairment on the C.P. Crane plant is included in "Impairments" on the Statement of Income.
[2]	Represents carrying value before fair value measurement.
[3]	For the Sapphire portfolio, also reflects estimated cost to sell.
[4]	The range and weighted average represent the percentage of fair value derived from the unobservable inputs.

Fair Value Measurements and C65

Fair Value Measurements and Credit Concentration (Financial Instruments Not Recorded at Fair Value and Credit Concentration) (Details) $ in Millions	Sep. 30, 2015USD ($)counterparty	Dec. 31, 2014USD ($)
Credit Concentration Associated with Financial Instruments (Numeric) [Abstract]
Gross credit exposure from energy trading partners	$ 554
Net credit exposure to energy trading partners	351
Dollar exposure to top ten energy trading counterparties	$ 170
Percentage exposure to top ten energy trading counterparties	48.00%
Number of counterparties in top ten that have investment grade credit rating | counterparty	9
Percentage of top ten's exposure that consists of counterparties with investment grade credit rating	91.00%
Carrying Amount
Fair Value of Financial Instruments Not Recorded at Fair Value - Other
Long-term debt	$ 4,030	$ 2,218
Fair Value
Fair Value of Financial Instruments Not Recorded at Fair Value - Other
Long-term debt	$ 3,717	$ 2,204

Derivative Instruments and He66

Derivative Instruments and Hedging Activities (Intro) (Details)		3 Months Ended		9 Months Ended
		Sep. 30, 2015USD ($)MW	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)MW	Sep. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Commodity Price Risk (Non-trading) [Abstract]
Generation fleet capacity (in MW) | MW		15,053		15,053
Cash Flow Hedges
Net unrealized after-tax gains (losses) expected to be reclassified into earnings within 12 months related to commodity price risk cash flow hedge contracts		$ 14,000,000		$ 14,000,000
Commodity Price Risk Nontrading Economic Activity Numeric [Abstract]
Year of expiration of the maximum maturity date of economic activity derivative contracts				2,020
Wholesale energy
Pre-tax Gains (Losses) of Economic Activity (Details) [Abstract]
Pre-tax gain (loss)	[1]	(77,000,000)	$ 299,000,000	$ (234,000,000)	$ (581,000,000)
Unrealized gain from change in valuation technique		30,000,000
Retail Energy
Pre-tax Gains (Losses) of Economic Activity (Details) [Abstract]
Pre-tax gain (loss)		(3,000,000)	2,000,000	(25,000,000)	(20,000,000)
Fuel
Pre-tax Gains (Losses) of Economic Activity (Details) [Abstract]
Pre-tax gain (loss)		(3,000,000)	(9,000,000)	13,000,000	(3,000,000)
Energy purchases
Pre-tax Gains (Losses) of Economic Activity (Details) [Abstract]
Pre-tax gain (loss)	[1]	130,000,000	$ (217,000,000)	370,000,000	402,000,000
Credit risk
Master Netting Arrangements
Obligation to return counterparty cash collateral under master netting arrangements		7,000,000		7,000,000		$ 11,000,000
Cash collateral posted under master netting arrangements		$ 0		$ 0		$ 0
Price Risk Derivative
Pre-tax Gains (Losses) of Economic Activity (Details) [Abstract]
Net energy trading margins					$ 58,000,000
[1]	In the third quarter of 2015, Talen Energy refined an input used in its valuation technique for certain PJM basis curves as observable inputs became available. This change resulted in the recording of a $30 million net unrealized gain, primarily reflected in "Wholesale energy" revenue on the Statement of Income.

Derivative Instruments and He67

Derivative Instruments and Hedging Activities (Commodity Volumes) (Details)	Sep. 30, 2015MMBTUMWhMW-MTbbl	[2]
Power | Sales | 2015
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	13,407,010	[1]
Power | Sales | 2016
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	29,872,806
Power | Sales | 2017
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	1,202,348
Power | Sales | Thereafter
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	795,983
Capacity | Sales | 2015
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu)	538	[1]
Capacity | Sales | 2016
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu)	878
Capacity | Purchases | 2017
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu)	6
Capacity | Purchases | Thereafter
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu)	3
Gas | Purchases | 2015
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MMBTU	61,373,321	[1]
Gas | Purchases | 2016
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MMBTU	98,156,219
Gas | Purchases | 2017
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MMBTU	15,586,507
Gas | Purchases | Thereafter
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MMBTU	19,636,898
FTRs | Purchases | 2015
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu)	2,023	[1]
FTRs | Purchases | 2016
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu)	2,889
FTRs | Purchases | 2017
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu)	0
FTRs | Purchases | Thereafter
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu)	0
Oil | Purchases | 2015
Derivative [Line Items]
Volumes (in barrels) | bbl	29,795	[1]
Oil | Purchases | 2016
Derivative [Line Items]
Volumes (in barrels) | bbl	60,000
Oil | Purchases | 2017
Derivative [Line Items]
Volumes (in barrels) | bbl	0
Oil | Purchases | Thereafter
Derivative [Line Items]
Volumes (in barrels) | bbl	0
CRR purchase contracts | Purchases | 2015
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	475,320	[1]
CRR purchase contracts | Purchases | 2016
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	1,393,430
CRR purchase contracts | Purchases | 2017
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	538,584
CRR purchase contracts | Purchases | Thereafter
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	0
Emission Allowances | Purchases | 2015
Derivative [Line Items]
Volumes (tons) | T	2,253,123	[1]
Emission Allowances | Purchases | 2016
Derivative [Line Items]
Volumes (tons) | T	0
Emission Allowances | Purchases | 2017
Derivative [Line Items]
Volumes (tons) | T	0
Emission Allowances | Purchases | Thereafter
Derivative [Line Items]
Volumes (tons) | T	0
[1]	Represents balance of the current year.
[2]	Volumes for option contracts factor in the probability of an option being exercised and may be less than the notional amount of the option.

Derivative Instruments and He68

Derivative Instruments and Hedging Activities (Fair Values) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Fair Values by Balance Sheet Location [Abstract]
Asset value	$ 802	$ 1,318
Liability value	684	1,217
Not Designated as Hedging Instrument
Fair Values by Balance Sheet Location [Abstract]
Asset value	802	1,318
Liability value	684	1,217
Not Designated as Hedging Instrument | Current Assets | Energy Commodities, net
Fair Values by Balance Sheet Location [Abstract]
Asset value	576	1,079
Not Designated as Hedging Instrument | Noncurrent Assets | Energy Commodities, net
Fair Values by Balance Sheet Location [Abstract]
Asset value	226	239
Not Designated as Hedging Instrument | Current Liabilities | Energy Commodities, net
Fair Values by Balance Sheet Location [Abstract]
Liability value	506	1,024
Not Designated as Hedging Instrument | Noncurrent Liabilities | Energy Commodities, net
Fair Values by Balance Sheet Location [Abstract]
Liability value	$ 178	$ 193

Derivative Instruments and He69

Derivative Instruments and Hedging Activities (Gains and Losses) (Details) - Energy Commodities, net - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014		Sep. 30, 2015	Sep. 30, 2014
Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	$ 6	$ 7		$ 23	$ 29
Cash Flow Hedges | Wholesale energy
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	(3)	(2)		(3)	(1)
Cash Flow Hedges | Energy purchases
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	9	8		25	23
Cash Flow Hedges | Depreciation
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	0		1	1
Cash Flow Hedges | Discontinued operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)		1			6
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivative, net	124	124		138	(614)
Not Designated as Hedging Instrument | Wholesale energy
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivative, net	298	617	[1]	328	(2,520)	[1]
Not Designated as Hedging Instrument | Retail Energy
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivative, net	15	18		(16)	(34)
Not Designated as Hedging Instrument | Fuel
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivative, net	(6)	(8)		(5)	(1)
Not Designated as Hedging Instrument | Energy purchases
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivative, net	$ (183)	(505)	[2]	$ (169)	1,937	[2]
Not Designated as Hedging Instrument | Discontinued operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivative, net		$ 2			$ 4
[1]	The nine month period ended September 30, 2014 includes significant realized and unrealized losses on physical and financial commodity sales contracts due to unusual market and weather volatility.
[2]	The nine month period ended September 30, 2014 includes significant realized and unrealized gains on physical and financial commodity purchase contracts due to unusual market and weather volatility.

Derivative Instruments and He70

Derivative Instruments and Hedging Activities (Offsetting Derivative Instruments and Credit Risk-Related Features) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Assets
Gross	$ 802	$ 1,318
Eligible for Offset, Derivative Instruments	567	1,060
Eligible for Offset, Cash Collateral Received	81	10
Net	154	248
Liabilities
Gross	684	1,217
Eligible for Offset, Derivative Instruments	567	1,060
Eligible for Offset, Cash Collateral Pledged	16	58
Net	101	$ 99
Derivative, Credit Risk Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position	99
Aggregate fair value of collateral posted on these derivative instruments	103
Aggregate fair value of additional collateral requirements, primarily related to further adequate assurance features	$ 19

Goodwill and Other Asset Impa71

Goodwill and Other Asset Impairments (Details) - USD ($)		3 Months Ended	9 Months Ended
		Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Goodwill, beginning balance			$ 72,000,000
Goodwill, ending balance		$ 0	0
Operating Segments | East
Goodwill [Line Items]
Goodwill impairment charge, before tax		466,000,000	466,000,000
Goodwill [Roll Forward]
Goodwill, beginning balance	[1]		72,000,000
Provisional goodwill recognized during the period	[2]		394,000,000
Goodwill impairment charge, before tax		(466,000,000)	(466,000,000)
Goodwill, ending balance	[1]	0	0
Accumulated impairment losses		$ 466,000,000	$ 466,000,000	$ 0
[1]	There were no accumulated impairment losses related to goodwill at December 31, 2014 and $466 million at September 30, 2015.
[2]	Recognized as a result of the acquisition of RJS Power. See Note 7 for additional information.

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at Beginning of Period	$ 425
Accretion expense	25
Changes in estimate of cash flow or settlement date	21
Obligations assumed in RJS Power acquisition	11
Obligations incurred	3
Obligations settled	(2)
Balance at End of Period	$ 483

Available-for-Sale Securities73

Available-for-Sale Securities (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Amortized cost - maturity less than 1 year		$ 11		$ 11
Amortized cost - maturity between 1 and 5 years		89		89
Amortized cost - maturity between 6 and 10 years		71		71
Amortized cost - maturity in excess of 10 years		62		62
Amortized cost total		233		233
Fair value - maturity less than 1 year		11		11
Fair value - maturity between 1 and 5 years		91		91
Fair value - maturity between 6 and 10 years		73		73
Fair value - maturity in excess of 10 years		66		66
Fair value total		241		241
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Proceeds from sales of NDT securities		43	$ 47	143	$ 112
Other proceeds from sales		0	3	0	6
Gross realized gains	[1]	6	9	19	17
Gross realized losses	[1]	7	$ 2	16	$ 6
NDT Funds
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		532		532		$ 522
Gross unrealized gains		381		381		428
Gross unrealized losses		0		0		0
Fair value		913		913		950
NDT Funds | Cash and cash equivalents
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		13		13		19
Gross unrealized gains		0		0		0
Gross unrealized losses		0		0		0
Fair value		13		13		19
NDT Funds | Equity securities
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		292		292		283
Gross unrealized gains		373		373		417
Gross unrealized losses		0		0		0
Fair value		665		665		700
NDT Funds | Debt securities
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		227		227		218
Gross unrealized gains		8		8		11
Gross unrealized losses		0		0		0
Fair value		235		235		229
NDT Funds | Receivables/payables, net
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		0		0		2
Gross unrealized gains		0		0		0
Gross unrealized losses		0		0		0
Fair value		0		0		2
Auction Rate Securities
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		6		6		8
Gross unrealized gains		0		0		0
Gross unrealized losses		0		0		0
Fair value		$ 6		$ 6		$ 8
[1]	Excludes the impact of other-than-temporary impairment charges recognized on the Statements of Income.

Accumulated Other Comprehensi74

Accumulated Other Comprehensive Income (Loss) (After-tax Changes by Component) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			$ (23)	$ 77
Amounts arising during the period			21	18
Reclassifications from accumulated other comprehensive income			(4)	(17)
Total other comprehensive income (loss)	$ (23)	$ (7)	17	1
Balance at end of period	(6)	78	(6)	78
Available- for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			202	173
Amounts arising during the period			(21)	18
Reclassifications from accumulated other comprehensive income			(1)	(5)
Total other comprehensive income (loss)			(22)	13
Balance at end of period	180	186	180	186
Qualifying derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			63	88
Amounts arising during the period			0	0
Reclassifications from accumulated other comprehensive income			(14)	(18)
Total other comprehensive income (loss)			(14)	(18)
Balance at end of period	49	70	49	70
Prior service costs
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			7	(4)
Amounts arising during the period			(4)	0
Reclassifications from accumulated other comprehensive income			(1)	2
Total other comprehensive income (loss)			(5)	2
Balance at end of period	2	(2)	2	(2)
Actuarial gain (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			(295)	(180)
Amounts arising during the period			46	0
Reclassifications from accumulated other comprehensive income			12	4
Total other comprehensive income (loss)			58	4
Balance at end of period	$ (237)	$ (176)	$ (237)	$ (176)

Accumulated Other Comprehensi75

Accumulated Other Comprehensive Income (Loss) (Income (Expense) Effect of Reclassifications) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Affected Line Item on the Statements of Income [Line Items]
Wholesale energy	$ 986	$ 1,109	$ 2,181	$ 203
Energy purchases	(298)	(708)	(588)	893
Other Income (Expense) - net	1	10	11	23
Total Pre-tax	(300)	168	(169)	54
Income Taxes	(39)	(74)	(49)	(16)
Income (Loss) from Continuing Operations After Income Taxes	(339)	94	(218)	38
Reclassification out of AOCI
Affected Line Item on the Statements of Income [Line Items]
Income (Loss) from Continuing Operations After Income Taxes	0	6	4	17
Reclassification out of AOCI | Available-for-sale securities
Affected Line Item on the Statements of Income [Line Items]
Other Income (Expense) - net	(1)	7	3	11
Income Taxes	0	(4)	(2)	(6)
Income (Loss) from Continuing Operations After Income Taxes	(1)	3	1	5
Reclassification out of AOCI | Qualifying derivatives
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	6	7	23	29
Income Taxes	(2)	(2)	(9)	(11)
Income (Loss) from Continuing Operations After Income Taxes	4	5	14	18
Reclassification out of AOCI | Qualifying derivatives | Commodity contracts
Affected Line Item on the Statements of Income [Line Items]
Wholesale energy	(3)	(2)	(3)	(1)
Energy purchases	9	8	25	23
Discontinued operations	0	1	0	6
Other Income (Expense) - net	0	0	1	1
Reclassification out of AOCI | Defined benefit plans
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	(5)	(3)	(19)	(10)
Income Taxes	2	1	8	4
Income (Loss) from Continuing Operations After Income Taxes	(3)	(2)	(11)	(6)
Reclassification out of AOCI | Defined benefit plans | Prior service costs
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	0	(2)	1	(4)
Reclassification out of AOCI | Defined benefit plans | Net actuarial loss
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	$ (5)	$ (1)	$ (20)	$ (6)

Uncategorized Items - tln-20150

Label	Element	Value
Retained Earnings [Member]
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	$ (311)
Predecessor Member's Equity [Member]
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	$ 32	[1]
[1]	Represents Talen Energy Supply's predecessor member's equity balance and activity prior to the June 1, 2015 spinoff transaction.