Talen Energy Supply 10-Q 5 Aug 16 2016 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Jul. 29, 2016
Entity Registrant Name	TALEN ENERGY CORPORATION
Entity Central Index Key	1,622,536
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		128,526,720
Talen Energy Supply
Entity Registrant Name	TALEN ENERGY SUPPLY, LLC
Entity Central Index Key	1,161,976
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Operating Revenues
Wholesale energy	$ 389	$ 561	$ 1,189	$ 1,237
Retail energy	189	243	448	554
Energy-related businesses	119	144	233	248
Total Operating Revenues	697	948	1,870	2,039
Operation
Fuel and energy purchases	347	382	838	897
Operation and maintenance	277	306	559	528
(Gain) loss on sale	(423)	0	(563)	0
Impairments	213	0	213	0
Depreciation	109	87	218	164
Taxes, other than income	11	5	22	8
Energy-related businesses	115	133	224	229
Total Operating Expenses	649	913	1,511	1,826
Operating Income (Loss)	48	35	359	213
Other Income (Expense) - net	6	3	12	10
Interest Expense	60	55	120	91
Income (Loss) Before Income Taxes	(6)	(17)	251	132
Income Taxes	(3)	(43)	103	10
Net Income (Loss)	$ (3)	$ 26	$ 148	$ 122
Earnings Per Share of Common Stock
Basic (in dollars per share)	$ (0.02)	$ 0.26	$ 1.15	$ 1.34
Diluted (in dollars per share)	$ (0.02)	$ 0.26	$ 1.14	$ 1.34
Weighted-Average Shares of Common Stock Outstanding (in thousands)
Basic (in shares)	128,527	98,354	128,526	90,980
Diluted (in shares)	128,527	98,376	129,475	91,002
Talen Energy Supply
Operating Revenues
Wholesale energy	$ 389	$ 561	$ 1,189	$ 1,237
Retail energy	189	243	448	554
Energy-related businesses	119	144	233	248
Total Operating Revenues	697	948	1,870	2,039
Operation
Fuel and energy purchases	347	382	838	897
Operation and maintenance	266	306	548	528
(Gain) loss on sale	(423)	0	(563)	0
Impairments	213	0	213	0
Depreciation	109	87	218	164
Taxes, other than income	11	5	22	8
Energy-related businesses	115	133	224	229
Total Operating Expenses	638	913	1,500	1,826
Operating Income (Loss)	59	35	370	213
Other Income (Expense) - net	6	3	12	10
Interest Expense	60	55	120	91
Income (Loss) Before Income Taxes	5	(17)	262	132
Income Taxes	1	(43)	107	10
Net Income (Loss)	$ 4	$ 26	$ 155	$ 122

CONDENSED CONSOLIDATED STATEME3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net income (loss)	$ (3)	$ 26	$ 148	$ 122
Amounts arising during the period - gains (losses), net of tax (expense) benefit:
Available-for-sale securities, net of tax	8	(4)	11	1
Prior service costs, net of tax	0	(3)	0	(3)
Net actuarial gain, net of tax	0	46	0	46
Reclassifications from AOCI - (gains) losses, net of tax expense (benefit):
Available-for-sale securities, net of tax	(3)	(1)	(2)	(2)
Qualifying derivatives, net of tax	(4)	(6)	(7)	(10)
Defined benefit plans:
Prior service costs, net of tax	0	(1)	0	(1)
Net actuarial loss, net of tax	4	5	7	9
Total other comprehensive income (loss)	5	36	9	40
Comprehensive income (loss)	2	62	157	162
Talen Energy Supply
Net income (loss)	4	26	155	122
Amounts arising during the period - gains (losses), net of tax (expense) benefit:
Available-for-sale securities, net of tax	8	(4)	11	1
Prior service costs, net of tax	0	(3)	0	(3)
Net actuarial gain, net of tax	0	46	0	46
Reclassifications from AOCI - (gains) losses, net of tax expense (benefit):
Available-for-sale securities, net of tax	(3)	(1)	(2)	(2)
Qualifying derivatives, net of tax	(4)	(6)	(7)	(10)
Defined benefit plans:
Prior service costs, net of tax	0	(1)	0	(1)
Net actuarial loss, net of tax	4	5	7	9
Total other comprehensive income (loss)	5	36	9	40
Comprehensive income (loss)	$ 9	$ 62	$ 164	$ 162

CONDENSED CONSOLIDATED STATEME4

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Tax effect of available for sale securities arising during the period	$ (9)	$ 5	$ (12)	$ (1)
Tax effect of prior service costs for defined benefit plans	0	2	0	2
Tax effect of net actuarial gain for defined benefit plans	0	(30)	0	(30)
Tax effect of available-for-sale securities reclassified from accumulated other comprehensive income (loss)	3	1	2	2
Tax effect of qualifying derivatives reclassified from accumulated other comprehensive income (loss)	3	4	5	7
Tax effect of prior service costs reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Tax effect of net actuarial loss reclassified from accumulated other comprehensive income (loss)	(2)	(3)	(4)	(6)
Talen Energy Supply
Tax effect of available for sale securities arising during the period	(9)	5	(12)	(1)
Tax effect of prior service costs for defined benefit plans	0	2	0	2
Tax effect of net actuarial gain for defined benefit plans	0	(30)	0	(30)
Tax effect of available-for-sale securities reclassified from accumulated other comprehensive income (loss)	3	1	2	2
Tax effect of qualifying derivatives reclassified from accumulated other comprehensive income (loss)	3	4	5	7
Tax effect of prior service costs reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Tax effect of net actuarial loss reclassified from accumulated other comprehensive income (loss)	$ (2)	$ (3)	$ (4)	$ (6)

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash Flows from Operating Activities
Net income (loss)	$ 148	$ 122
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Pre-tax gain from the sale of certain generation facilities	(595)	0
Depreciation	218	164
Amortization	93	93
Defined benefit plans - expense	23	23
Deferred income taxes and investment tax credits	(142)	(46)
Impairment of assets	214	6
Unrealized (gains) losses on derivatives, and other hedging activities	83	(40)
Other	17	38
Change in current assets and current liabilities
Accounts receivable	(18)	50
Accounts payable	(28)	(135)
Unbilled revenues	24	80
Fuel, materials and supplies	23	33
Prepayments	(5)	37
Counterparty collateral	(57)	36
Taxes payable	212	(2)
Other	(10)	(33)
Other operating activities
Defined benefit plans - funding	0	(74)
Other assets	3	2
Other liabilities	4	1
Net cash provided by operating activities	207	355
Cash Flows from Investing Activities
Expenditures for property, plant and equipment	(268)	(179)
Proceeds from the sale of certain generation facilities	1,525	0
Expenditures for intangible assets	(29)	(19)
Purchases of nuclear plant decommissioning trust investments	(101)	(108)
Proceeds from the sale of nuclear plant decommissioning trust investments	92	100
Net (increase) decrease in restricted cash and cash equivalents	53	67
Other investing activities	18	12
Net cash provided by (used in) investing activities	1,290	(127)
Cash Flows from Financing Activities
Issuance of long-term debt	0	600
Retirement of long-term debt	(394)	(2)
Contributions from predecessor member	0	82
Distributions to predecessor member	0	(214)
Net increase (decrease) in short-term debt	(150)	(668)
Other financing activities	(3)	(26)
Net cash provided by (used in) financing activities	(547)	(228)
Net Increase (Decrease) in Cash and Cash Equivalents	950	0
Cash and Cash Equivalents at Beginning of Period	141	352
Cash and Cash Equivalents at End of Period	1,091	352
Talen Energy Supply
Cash Flows from Operating Activities
Net income (loss)	155	122
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Pre-tax gain from the sale of certain generation facilities	(595)	0
Depreciation	218	164
Amortization	93	93
Defined benefit plans - expense	23	23
Deferred income taxes and investment tax credits	(137)	(46)
Impairment of assets	214	6
Unrealized (gains) losses on derivatives, and other hedging activities	83	(40)
Other	17	38
Change in current assets and current liabilities
Accounts receivable	(27)	50
Accounts payable	(31)	(135)
Unbilled revenues	24	80
Fuel, materials and supplies	23	33
Prepayments	(5)	37
Counterparty collateral	(57)	36
Taxes payable	212	(2)
Other	(10)	(33)
Other operating activities
Defined benefit plans - funding	0	(74)
Other assets	3	2
Other liabilities	4	1
Net cash provided by operating activities	207	355
Cash Flows from Investing Activities
Expenditures for property, plant and equipment	(268)	(179)
Proceeds from the sale of certain generation facilities	1,525	0
Expenditures for intangible assets	(29)	(19)
Purchases of nuclear plant decommissioning trust investments	(101)	(108)
Proceeds from the sale of nuclear plant decommissioning trust investments	92	100
Net (increase) decrease in restricted cash and cash equivalents	53	67
Other investing activities	18	12
Net cash provided by (used in) investing activities	1,290	(127)
Cash Flows from Financing Activities
Issuance of long-term debt	0	600
Retirement of long-term debt	(394)	(2)
Contributions from predecessor member	0	82
Distributions to predecessor member	0	(215)
Net increase (decrease) in short-term debt	(150)	(668)
Other financing activities	(3)	(25)
Net cash provided by (used in) financing activities	(547)	(228)
Net Increase (Decrease) in Cash and Cash Equivalents	950	0
Cash and Cash Equivalents at Beginning of Period	141	352
Cash and Cash Equivalents at End of Period	$ 1,091	$ 352

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Current Assets
Cash and cash equivalents		$ 1,091	$ 141
Restricted cash and cash equivalents		53	106
Accounts receivable (less reserve:)
Customer		220	205
Other		53	62
Unbilled revenues		136	160
Fuel, materials and supplies		482	508
Prepayments		57	52
Price risk management assets		429	562
Assets held for sale		0	954
Other current assets		14	12
Total Current Assets		2,535	2,762
Investments
Nuclear plant decommissioning trust funds		984	951
Other investments		18	25
Total Investments		1,002	976
Property, Plant and Equipment
Generation		13,607	13,468
Nuclear fuel		650	652
Other		348	342
Less: accumulated depreciation		6,533	6,411
Property, plant and equipment, net		8,072	8,051
Construction work in progress		492	536
Total Property, Plant and Equipment, net		8,564	8,587
Other Noncurrent Assets
Other intangibles		105	310
Price risk management assets		153	131
Other noncurrent assets		44	43
Total Other Noncurrent Assets		302	484
Total Assets		12,403	12,809
Current Liabilities
Short-term debt		350	608
Long-term debt due within one year		5	399
Accounts payable		262	291
Taxes		228	16
Interest		40	43
Price risk management liabilities		393	431
Liabilities held for sale		0	33
Counterparty collateral		22	79
Other current liabilities		182	188
Total Current Liabilities		1,482	2,088
Long-term Debt		3,896	3,787
Deferred Credits and Other Noncurrent Liabilities
Deferred income taxes		1,461	1,587
Investment tax credits		9	15
Price risk management liabilities		127	108
Accrued pension obligations		352	340
Asset retirement obligations		501	490
Other deferred credits and noncurrent liabilities		110	91
Total Deferred Credits and Other Noncurrent Liabilities		2,560	2,631
Commitments and Contingent Liabilities
Equity
Common Stock - $0.001 par value	[1]	0	0
Additional paid-in capital		4,707	4,702
Accumulated deficit		(225)	(373)
Accumulated other comprehensive income (loss)		(17)	(26)
Total Equity		4,465	4,303
Total Liabilities and Equity		12,403	12,809
Talen Energy Supply
Current Assets
Cash and cash equivalents		1,091	141
Restricted cash and cash equivalents		53	106
Accounts receivable (less reserve:)
Customer		220	205
Other		53	62
Accounts receivable from affiliates		9	0
Unbilled revenues		136	160
Fuel, materials and supplies		482	508
Prepayments		57	52
Price risk management assets		429	562
Assets held for sale		0	954
Other current assets		14	12
Total Current Assets		2,544	2,762
Investments
Nuclear plant decommissioning trust funds		984	951
Other investments		18	25
Total Investments		1,002	976
Property, Plant and Equipment
Generation		13,607	13,468
Nuclear fuel		650	652
Other		348	342
Less: accumulated depreciation		6,533	6,411
Property, plant and equipment, net		8,072	8,051
Construction work in progress		492	536
Total Property, Plant and Equipment, net		8,564	8,587
Other Noncurrent Assets
Other intangibles		105	310
Price risk management assets		153	131
Other noncurrent assets		44	43
Total Other Noncurrent Assets		302	484
Total Assets		12,412	12,809
Current Liabilities
Short-term debt		350	608
Long-term debt due within one year		5	399
Accounts payable		259	291
Taxes		228	16
Interest		40	43
Price risk management liabilities		393	431
Liabilities held for sale		0	33
Counterparty collateral		22	79
Other current liabilities		182	188
Total Current Liabilities		1,479	2,088
Long-term Debt		3,896	3,787
Deferred Credits and Other Noncurrent Liabilities
Deferred income taxes		1,466	1,587
Investment tax credits		9	15
Price risk management liabilities		127	108
Accrued pension obligations		352	340
Asset retirement obligations		501	490
Other deferred credits and noncurrent liabilities		110	91
Total Deferred Credits and Other Noncurrent Liabilities		2,565	2,631
Commitments and Contingent Liabilities
Equity
Member's Equity		4,472	4,303
Total Liabilities and Equity		$ 12,412	$ 12,809
[1]	1,000,000 shares authorized at June 30, 2016 and December 31, 2015; 128,527 and 128,509 shares issued and outstanding at June 30, 2016 and December 31, 2015.

CONDENSED CONSOLIDATED BALANCE7

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Accounts receivable reserve for uncollectible accounts	$ 1	$ 1
Par value, common stock (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Shares outstanding, common stock (in shares)	128,527,000	128,509,000
Shares issued, common stock (in shares)	128,527,000	128,509,000
Talen Energy Supply
Accounts receivable reserve for uncollectible accounts	$ 1	$ 1

CONDENSED CONSOLIDATED STATEME8

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Millions		Total		Common Stock		Additional Paid-in Capital	Accumulated earnings (deficit)	AOCI	Predecessor member's equity	[1]	Talen Energy Supply
Beginning balance at Dec. 31, 2014		$ 3,907				$ 0	$ 0	$ (23)	$ 3,930
Beginning balance, shares at Dec. 31, 2014	[2]			0
Beginning balance at Dec. 31, 2014											$ 3,907
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		122									122
Other comprehensive income (loss)		40						40			40
Distributions to member		(396)	[1]						(396)		(397)
Contributions from member		250	[1]						250		1,154	[3]
Common stock issued for acquisition of RJS Power (shares)	[2],[4]			44,975
Common stock issued for acquisition of RJS Power	[4]	902				902
Stock issuance (shares)	[2]			10
Stock issuance expense		(1)				(1)
Stock-based compensation		2				2
Consummation of spinoff transaction (shares)	[2],[4]			83,524
Consummation of spinoff transaction	[4]	0				3,816			(3,816)
Ending balance at Jun. 30, 2015		4,826				4,719	90	17	0
Ending balance, shares at Jun. 30, 2015	[2]			128,509
Ending balance at Jun. 30, 2015											4,826
Beginning balance at Dec. 31, 2015		$ 4,303				4,702	(373)	(26)	0
Beginning balance, shares at Dec. 31, 2015		128,509		128,509	[2]
Beginning balance at Dec. 31, 2015											4,303
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		$ 148					148				155
Other comprehensive income (loss)		9						9			9
Contributions from member	[5]										5
Stock issuance (shares)	[2]			18
Stock-based compensation		7				7
Consummation of spinoff transaction (shares)	[2],[4]			0
Consummation of spinoff transaction	[4]	(2)				(2)			0
Ending balance at Jun. 30, 2016		$ 4,465				$ 4,707	$ (225)	$ (17)	$ 0
Ending balance, shares at Jun. 30, 2016		128,527		128,527	[2]
Ending balance at Jun. 30, 2016											$ 4,472
[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 Note 1 in Talen Energy's Form 10-K 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 in Talen Energy's Form 10-K for additional information on the spinoff. The amount in 2016 represents a correction to the June 1, 2015 predecessor member's equity for a contribution received from PPL.
[5]	Primarily represents non-cash stock compensation partially offset by an insignificant reduction for the correction of a contribution received from PPL as part of the June 1, 2015 spinoff.

Business and Basis of Presentat

Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2016
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. As Talen Energy Corporation is substantially comprised of Talen Energy Supply, LLC and its subsidiaries, to avoid repetition, most disclosures refer to Talen Energy which indicates the disclosure applies to Talen Energy Corporation and Talen Energy Supply, LLC. This presentation has been applied where identification of particular subsidiaries is not material to the matter being disclosed, and to conform narrative disclosures to the presentation of financial information on a consolidated basis. When identification of a particular registrant or subsidiary is considered important to understanding the matter being disclosed, the specific entity's name is used, in particular, for those few disclosures that apply only to Talen Energy Corporation. Each disclosure referring to a subsidiary applies to both Talen Energy Corporation and Talen Energy Supply and each disclosure referring to Talen Energy Supply applies to Talen Energy Corporation through consolidation. Business Talen Energy Corporation, through its principal subsidiary Talen Energy Supply, is a North American competitive power generation and marketing company primarily engaged in the production and sale of electricity, capacity and ancillary products. Talen Energy is headquartered in Allentown, Pennsylvania and owns and operates a portfolio of generation assets principally located in the Northeast, Mid-Atlantic and Southwest regions of the U.S. See "Item 1. Business" in Talen Energy's 2015 Form 10-K for a discussion of Talen Energy's business, including the June 2015 spinoff from PPL and formation of Talen Energy Corporation. In June 2016, Talen Energy Corporation announced the Merger with affiliates of Riverstone Holdings LLC, a private investment firm, in which all outstanding shares of common stock not owned by Riverstone affiliated entities will be acquired, subject to certain exceptions. The transaction is expected to be completed by the end of 2016, subject to regulatory and stockholder approval and satisfaction of other closing conditions. See Note 7 for additional information. Spinoff from PPL Following the June 2015 spinoff from PPL, 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 six months ended June 30, 2016 , the costs incurred for these services were $10 million and $22 million . The costs incurred for these services during the three and six months ended June 30, 2015 were not significant. In connection with the spinoff transaction in 2015, 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 three and six months ended June 30, 2015 , Talen Energy Supply recorded $25 million related to these accelerated stock-based compensation and pro-rated stock-based compensation awards. The vesting for all Talen Energy Supply employees was accelerated and all remaining unrecognized compensation expense was accelerated concurrently with the spinoff. See Note 8 in Talen Energy's 2015 Form 10-K for additional information on stock-based compensation. In addition, during the three and six months ended June 30, 2015 , Talen Energy incurred $8 million and $10 million of restructuring costs related to the spinoff transaction which are recorded in "Operation and maintenance" on the Statements of Income. Basis of Presentation 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, 2015 are derived from Talen Energy's 2015 audited Balance Sheet. The financial statements and notes thereto should be read in conjunction with the financial statements and notes contained in Talen Energy's 2015 Form 10-K. The results of operations for the three and six months ended June 30, 2016 are not necessarily indicative of the results to be expected for the full year ending December 31, 2016 or other future periods, because results for interim periods can be disproportionately influenced by various factors, developments and seasonal variations. Talen Energy Supply is considered the accounting predecessor of Talen Energy Corporation. Therefore, the financial information prior to the June 2015 spinoff 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 six months of legacy Talen Energy Supply information consolidated with one month of RJS information from June 1, 2015. Talen Energy completed the acquisition of MACH Gen in November 2015. MACH Gen's operating results for the three and six months ended June 30, 2016 are included in Talen Energy's results of operations with no comparable amounts for the same period in 2015. The assets and liabilities related to the Holtwood, Lake Wallenpaupack, C.P. Crane and Ironwood facilities were classified as "Assets held for sale" and "Liabilities held for sale" at December 31, 2015. See Note 8 for additional information on these divestitures. The sales of Talen Ironwood Holdings, LLC and C.P. Crane LLC were completed in February 2016 and the sale of the Holtwood and Lake Wallenpaupack hydroelectric facilities was completed in April 2016. The sales satisfied the requirement to divest certain PJM assets to comply with a December 2014 FERC order approving the combination with RJS Power. The classification of certain prior period amounts has been changed to conform to the presentation in the June 30, 2016 financial statements as discussed below. In these financial statements, revenue and expense from derivatives is recorded based on Talen Energy's economic hedging strategy. For example, all purchases and sales associated with economic hedging of the sale of energy using contracts accounted for as derivatives are recorded within "Operating Revenues" and all purchases and sales associated with economic hedging of the procurement of fuel or purchasing energy using contracts accounted for as derivatives are recorded as "Operating Expenses" on the Statements of Income. Prior to the fourth quarter of 2015, Talen Energy classified all non-trading commodity hedge transactions as revenue or expense based upon whether each specific transaction was a sale or purchase, which in certain instances, created losses within revenue and gains within expense. As a result of this change in presentation to previously reported 2015 amounts, there were equal and offsetting changes between "Operating Revenues" and "Operating Expenses" with no impact on "Operating Income (Loss)" on the 2015 Statement of Income. This change in presentation resulted in a decrease of $125 million for the three months ended June 30, 2015 and an increase of $20 million for the six months ended June 30, 2015 in "Wholesale energy" and "Fuel and energy purchases" on the Statement of Income. Also, presentation on the 2015 Statement of Income was modified to combine "Fuel" and "Energy purchases" in a single line item and to reclassify certain "Operating Expenses" to align the presentation of these operating expenses with how Talen Energy management views these costs. This change in presentation for certain operating expenses resulted in an increase of $15 million and $33 million for the three and six months ended June 30, 2015 to "Fuel and energy purchases" with offsetting decreases, primarily to "Taxes, other than income," but also to "Operation and maintenance" and "Energy-related businesses." This change had no impact on "Operating Income (Loss)" for the three and six months ended June 30, 2015 . In addition, the operating results of the Sapphire portfolio for the three and six months ended June 30, 2015 were reclassified to continuing operations as a result of the November 2015 FERC order approving the third mitigation package relating to the transactions that formed Talen Energy. This change in presentation resulted in an increase for the three and six months ended June 30, 2015 of $8 million to "Operating Revenues" and $7 million to "Operating Expenses." This change had an insignificant increase to "Operating Income (Loss)" for the three and six months ended June 30, 2015 . See Note 1 in Talen Energy's 2015 Form 10-K for additional information on the initial classification as discontinued operations and the November 2015 FERC Order. During the three and six months ended June 30, 2015 , Talen Energy recorded a $7 million decrease to "Retail energy" revenues on the Statements 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 Utilities Corporation. Such amounts should have been recognized as an affiliate payable, but were inadvertently recorded as revenue. The $4 million after-tax ( $0.04 per share for Talen Energy Corporation) impact of correcting this overstatement of "Retail energy" revenues decreased "Net Income (Loss)" during the three and six months ended June 30, 2015 . The impact of the overstatement was not material to the previously-issued financial statements and the correction was not material to the full year results for 2015.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The following accounting policy disclosure represents an update to Note 1 to the Financial Statements in Talen Energy's 2015 Form 10-K and should be read in conjunction with those disclosures. New Accounting Guidance Adopted Simplifying the Presentation of Debt Issuance Costs Effective January 1, 2016, Talen Energy adopted accounting guidance that simplifies 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. The initial adoption of this guidance required Talen Energy to reclassify long-term debt issuance costs on the Balance Sheet from assets to long-term debt. During the first quarter of 2016, Talen Energy retrospectively adopted this guidance. The December 31, 2015 Balance Sheet reflects a reclassification of $17 million between "Other noncurrent assets" and "Long-term debt" for the implementation. Issuance costs related to line-of-credit arrangements remain deferred as a long-term asset and amortized over the life of the arrangement. Accounting for Cloud Computing Arrangements Effective January 1, 2016, Talen Energy prospectively adopted guidance that clarifies how to determine if a cloud computing arrangement includes a software license. If a cloud computing arrangement contains a software license, the license should be accounted for in a manner consistent with the acquisition of other software licenses. If a cloud computing arrangement does not contain a software license, the arrangement should be accounted for as a service contract. The initial adoption of this guidance did not have a significant impact on Talen Energy. Because Talen Energy may enter into cloud computing arrangements that fall within the scope of this guidance, this guidance may have an impact in future periods.

Segment and Related Information

Segment and Related Information	6 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Segment and Related Information	Segment and Related Information See Note 2 in Talen Energy's 2015 Form 10-K for a discussion of reportable segments and related information. Financial data for the segments and reconciliation to consolidated results for the periods ended June 30 are: Three Months Six Months 2016 2015 2016 2015 Talen Energy Corporation - Income Statement Data Revenues from external customers (a) East $ 627 $ 895 $ 1,723 $ 1,942 West 70 53 147 97 Total $ 697 $ 948 $ 1,870 $ 2,039 Operating Income (Loss) East $ 152 $ 147 $ 544 $ 378 West (52 ) (20 ) (80 ) (21 ) Other (52 ) (92 ) (105 ) (144 ) Total $ 48 $ 35 $ 359 $ 213 Three Months Six Months 2016 2015 2016 2015 Talen Energy Supply - Income Statement Data Revenues from external customers (a) East $ 627 $ 895 $ 1,723 $ 1,942 West 70 53 147 97 Total $ 697 $ 948 $ 1,870 $ 2,039 Operating Income (Loss) East $ 152 $ 147 $ 544 $ 378 West (52 ) (20 ) (80 ) (21 ) Other (41 ) (92 ) (94 ) (144 ) Total $ 59 $ 35 $ 370 $ 213 Talen Energy Corporation Talen Energy Supply Balance Sheet Data June 30, 2016 December 31, 2015 June 30, 2016 December 31, 2015 Assets East $ 9,979 $ 11,430 $ 9,979 $ 11,430 West 1,273 1,231 1,273 1,231 Other (b) 1,151 148 1,160 148 Total Assets $ 12,403 $ 12,809 $ 12,412 $ 12,809 (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	6 Months Ended
	Jun. 30, 2016
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 six months ended June 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 June 30 used in the EPS calculation are: Three Months Six Months 2016 2015 2016 2015 Income (Numerator) Net Income (Loss) $ (3 ) $ 26 $ 148 $ 122 Shares of Common Stock (Denominator) Weighted-average shares - Basic EPS 128,527 98,354 128,526 90,980 Add incremental non-participating securities: Share-based payment awards — 22 949 22 Weighted-average shares - Diluted EPS 128,527 98,376 129,475 91,002 Share-based payment awards of 2,305 thousand shares and 1,225 thousand shares were excluded from the computations of diluted EPS for the three and six months ended June 30, 2016 because the effect would have been antidilutive.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Selected information regarding the income tax provision for the periods ended June 30 was as follows: Three Months Six Months 2016 2015 2016 2015 Talen Energy Corporation Income (Loss) Before Income Taxes $ (6 ) $ (17 ) $ 251 $ 132 Income Taxes $ (3 ) $ (43 ) $ 103 $ 10 Effective Tax Rate 50 % 253 % 41 % 8 % Talen Energy Supply Income (Loss) Before Income Taxes $ 5 $ (17 ) $ 262 $ 132 Income Taxes $ 1 $ (43 ) $ 107 $ 10 Effective Tax Rate 20 % 253 % 41 % 8 % Talen Energy recorded income taxes during the six month periods at an interim period annualized effective tax rate of 39.87% in 2016 compared with 32.52% in 2015 . However, Talen Energy's income tax expense reflected in the table above does not bear a customary relationship to income (loss) before income taxes primarily as a result of the impact of 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 three and six months ended June 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 three and six months ended June 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	6 Months Ended
	Jun. 30, 2016
Debt Disclosure [Abstract]
Financing Activities	Financing Activities Credit Arrangements and Short-term Debt Talen Energy maintains credit arrangements to enhance liquidity and provide credit support. For reporting purposes, on a consolidated basis, the credit arrangements of Talen Energy Supply and its subsidiaries also apply to Talen Energy Corporation. Revolving Credit Facilities The following secured revolving credit facilities were in place at: June 30, 2016 December 31, 2015 Expiration Date Capacity Borrowed Letters of Unused Capacity Borrowed Letters of Credit Issued Talen Energy Supply RCF (a) June 2020 $ 1,850 $ 350 $ 195 $ 1,305 $ 500 $ 163 New MACH Gen RCF (b) July 2021 160 108 31 21 108 31 Total Credit Facilities $ 2,010 $ 458 $ 226 $ 1,326 $ 608 $ 194 (a) The facility is syndicated and provides Talen Energy Supply the ability to make revolving cash borrowings and to request the lenders to issue up to $925 million of letters of credit, which in combination cannot exceed the capacity of the facility at any given time. The weighted average interest rate on outstanding borrowings was 2.70% and 2.67% at June 30, 2016 and December 31, 2015. The amounts borrowed are recorded as "Short-term debt" on the Balance Sheets. See Note 7 for information on expected changes to the facility capacity at the time of closing of the Merger. (b) The facility provides New MACH Gen the ability to make revolving cash borrowings and to request the lenders to issue up to $120 million of letters of credit, which in combination cannot exceed the capacity of the facility at any given time. The weighted average interest rate on outstanding borrowings was 5.42% and 5.04% at June 30, 2016 and December 31, 2015. The amounts borrowed are recorded on the Balance Sheets as "Long-term debt" at June 30, 2016 and as "Short-term debt" at December 31, 2015. The classification as current at December 31, 2015 was based on Talen Energy's intent and ability to repay outstanding borrowings within the next year. Other Facilities Talen Energy Supply is party to 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 June 30, 2016 , Talen Energy Supply had not requested any capacity for the issuance of letters of credit under this agreement. Talen Energy Supply is party to a $1.3 billion Amended STF Agreement that allows Talen Energy Supply to receive credit to satisfy collateral posting obligations related to Talen Energy's energy marketing and trading activities with counterparties participating in the facility. The facility became effective in December 2015 and has a five -year term ending December 2020 which automatically extends one -year on each anniversary of the effective date, subject to certain conditions. There were $63 million of secured obligations outstanding under this facility at June 30, 2016 . Long-term Debt In December 2015, Talen Energy Supply announced an "exchange offer" for its 6.5% Senior Unsecured Notes due 2025 that were issued in a private offering in May 2015. Pursuant to the terms of the notes, Talen Energy Supply offered to exchange all of the outstanding notes for a like principal amount of its 6.5% Senior Notes due 2025 that were registered under the Securities Act of 1933, as amended. In January 2016, the exchange offer was completed with all of the notes exchanged. In connection with the sale of Talen Ironwood Holdings, LLC, in January 2016, a Talen Ironwood Holdings, LLC subsidiary completed the redemption of $41 million of its 8.857% Senior Secured Notes due 2025 prior to the closing of the sale transaction, which occurred in February 2016. The redemption included the payment of a make whole premium of $14 million , which is reflected in "(Gain) loss on sale" on the Statement of Income and "Cash from operating activities" on the Statement of Cash Flows for the six months ended June 30, 2016. See Note 8 for additional information on the sale. In May 2016, $350 million of Talen Energy Supply's 6.2% Senior Unsecured Notes matured. Talen Energy Supply repaid the debt using short-term borrowings under the Talen Energy Supply RCF. See Note 7 for information on subsidiary guarantees of certain long-term debt in connection with the Merger.

Merger Agreement

Merger Agreement	6 Months Ended
	Jun. 30, 2016
Business Combinations [Abstract]
Merger Agreement	Merger Agreement On June 2, 2016, Talen Energy Corporation entered into an Agreement and Plan of Merger (the Merger Agreement) with RPH Parent LLC, SPH Parent LLC, CRJ Parent LLC (each, an affiliate of Riverstone, and collectively referred to as "Parent"), and RJS Merger Sub Inc. (a wholly owned subsidiary of Parent referred to as "Merger Sub"), pursuant to which Merger Sub will merge with and into Talen Energy Corporation (the Merger), with Talen Energy Corporation continuing as the surviving corporation on the terms and conditions set forth in the Merger Agreement. At the effective time of the Merger, each share of Talen Energy Corporation common stock outstanding immediately before the effective time of the Merger (excluding shares held by Parent, Merger Sub or certain affiliates of Riverstone and excluding shares pursuant to which dissenting rights under Delaware law have been properly exercised and not withdrawn or lost) will be automatically converted into the right to receive $14.00 in cash, without interest (the Merger Consideration). In addition, affiliates of Riverstone will convert, at the Effective Time, their existing ownership of approximately 35% of the issued and outstanding shares of Talen Energy Corporation common stock into shares of the surviving corporation. Talen Energy Corporation currently expects the transaction to be completed by the end of 2016, subject to regulatory and stockholder approval and satisfaction of other closing conditions. The Merger Consideration will be funded by Talen Energy's cash on hand and the proceeds of a new $250 million secured term loan. The new secured term loan is fully committed by certain lenders and will rank pari-passu with the Talen Energy Supply RCF, which, in accordance with a consent agreement entered into with the administrative agent and lenders under the Talen Energy Supply RCF, will be reduced from $1.85 billion to $1.4 billion upon closing of the transaction. The consummation of the Merger is subject to the affirmative vote of (i) a majority of the outstanding shares of Talen Energy Corporation common stock and (ii) a majority of the shares of Talen Energy Corporation common stock (A) not owned by Riverstone, its related entities and any of their respective affiliates and (B) present in person or by proxy at the stockholders meeting to be held with respect to the Merger. Consummation of the Merger also is conditioned on Talen Energy Corporation's satisfaction or receipt of a waiver of certain requirements of the separation agreement entered into in connection with the spinoff of Talen Energy Corporation from PPL (and certain related transactions), generally requiring the delivery of an IRS ruling or a tax opinion from a tax expert to the effect that the Merger will not jeopardize the intended tax-free treatment of the spinoff and certain related transactions. Consummation of the Merger is not subject to a financing condition, but is subject to a condition that Talen Energy Corporation has unrestricted cash and cash equivalents and undrawn revolver capacity equal to at least $350 million at closing, subject to certain exceptions, and after taking into account the proceeds of the new $250 million secured term loan discussed above. Consummation of the Merger is also subject to the condition that immediately prior to the closing, certain specified defaults and events of default under the Talen Energy Supply RCF shall not have occurred. The Merger Agreement contains certain termination rights, including the right of Talen Energy Corporation to terminate the Merger Agreement to accept a superior proposal, subject to specified limitations, and provides that, upon termination of the Merger Agreement by Talen Energy Corporation or Parent upon specified conditions, Talen Energy Corporation will be required to pay Parent a termination fee of $50 million . Upon termination of the Merger Agreement by Talen Energy Corporation or Parent under specified conditions, Parent will be required to pay Talen Energy Corporation a termination fee of $85 million . The Merger Agreement permitted Talen Energy Corporation and its advisors to actively solicit and negotiate alternative acquisition proposals from third parties during a "go-shop" period that began on June 2, 2016 and expired on July 12, 2016. No alternative proposals were received that would constitute a superior proposal under the Merger Agreement. Talen Energy Corporation is now subject to customary "no shop" restrictions prohibiting Talen Energy Corporation, its subsidiaries, directors, officers, employees and other representatives from soliciting alternative proposals from third parties or providing information to or participating in any discussions or negotiations with third parties regarding alternative proposals. These non-solicitation provisions are subject to a "fiduciary out" provision that allows Talen Energy Corporation to provide non-public information and participate in discussions and negotiations with respect to certain unsolicited written acquisition proposals and upon payment of the termination fee to terminate the Merger Agreement and enter into an alternative acquisition agreement if the Board of Directors determines in good faith after consultation with outside legal and financial advisors that such proposal constitutes a superior proposal under the terms of the Merger Agreement. In connection with entering into the Merger Agreement, the Riverstone Holders entered into a support agreement pursuant to which such parties have committed to vote their shares of Talen Energy Corporation common stock in favor of, and take certain other actions in furtherance of, the transactions contemplated by the Merger Agreement, including the Merger. On June 2, 2016, the subsidiaries that guarantee the Talen Energy Supply RCF agreed to unconditionally guarantee, effective upon the closing of the Merger and the other transactions contemplated by the Merger Agreement, all of Talen Energy Supply's obligations with respect to its 6.5% Senior Notes due 2025 and Exempt Facilities Revenue Refunding Bonds, Series 2009A, Series 2009B and Series 2009C. The Merger Agreement and the above summary of certain of its terms have been included to provide information regarding the terms of the Merger Agreement. Factual disclosures about Talen Energy Corporation contained in this report may supplement, update or modify the factual disclosures about Talen Energy Corporation contained in the Merger Agreement. The representations, warranties and covenants made in the Merger Agreement by Talen Energy Corporation, Parent and Merger Sub were qualified and subject to important limitations agreed to by Talen Energy Corporation, Parent and Merger Sub in connection with negotiating the terms of the Merger Agreement. The representations and warranties contained in the Merger Agreement were negotiated with the principal purposes of establishing the circumstances in which a party to the Merger Agreement may have the right not to close the Merger if the representations and warranties of the other party prove to be untrue due to a change in circumstance or otherwise, and allocating risk between the parties to the Merger Agreement, rather than establishing matters as facts. The representations and warranties may also be subject to a contractual standard of materiality different from those generally applicable to stockholders and reports and documents filed with the SEC. Moreover, information concerning the subject matter of the representations and warranties, which do not purport to be accurate as of the date of this report, (i) is contained, in part, on schedules to the Merger Agreement that have not been filed with the SEC in reliance upon applicable SEC regulations and (ii) may have changed since the date of the Merger Agreement and subsequent developments or new information qualifying a representation or warranty may or may not have been included in this report. For further information on the Merger, the Merger Agreement, the consent agreement, the support agreement and other Merger related agreements, please refer to the Current Report on Form 8-K filed on June 6, 2016 and the preliminary proxy statement filed on July 1, 2016 by Talen Energy Corporation. The foregoing descriptions of the Merger Agreement, the consent agreement and the support agreement are subject to, and qualified in their entirety by, the full text of those agreements as attached as exhibits to the Form 8-K filed on June 6, 2016, each of which is incorporated by reference herein. During the three and six months ended June 30, 2016 , Talen Energy Corporation recorded $11 million of expenses related to the Merger, primarily for investment banking, legal and other professional services, which are reflected in "Operation and maintenance" on the Statement of Income. In addition, Talen Energy will record accelerated stock-based compensation expense at close, which is currently estimated to be approximately $14 million .

Acquisitions, Development and D

Acquisitions, Development and Divestitures	6 Months Ended
	Jun. 30, 2016
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. Acquisitions MACH Gen See Note 6 in Talen Energy's 2015 Form 10-K for information on the November 2015 acquisition of the membership interests of MACH Gen. Various purchase accounting adjustments were made during the first and second quarters of 2016 that had an insignificant impact to PP&E and related deferred income taxes. The statement of income effect of these adjustments during the measurement period was also insignificant. The purchase price allocation is considered by Talen Energy's management to be final as of June 30, 2016. RJS Power Actual operating revenue and net income of RJS, since the June 1, 2015 acquisition, included in Talen Energy's results for the periods ended June 30, 2015 were: Three and Six Months Operating Revenues (a) Net Income $ 110 $ 14 (a) Operating Revenues have been adjusted to return Sapphire to continuing operations. See Note 1 for additional information on the reclassification. Pro forma information for Talen Energy for the periods ended June 30, 2015 as if the acquisition had occurred January 1, 2015, is as follows: Three Months Six Months Operating Revenues Income (Loss) After Tax from Continuing Operations Operating Revenues Income (Loss) After Tax from Continuing Operations Pro forma $ 1,056 $ 7 $ 2,378 $ 95 Basic and diluted earnings per share for Talen Energy Corporation 0.05 0.74 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) alignment of accounting policies, (2) incremental depreciation and amortization expense related to fair value adjustments to PP&E and identifiable intangible assets and liabilities, (3) incremental interest expense for outstanding borrowings to reflect the terms of the new syndicated credit facility, (4) nonrecurring items (discussed below), (5) the tax effect of the above adjustments, and (6) the issuance of Talen Energy Corporation common stock in connection with the spinoff from PPL and the acquisition of RJS Power. Nonrecurring acquisition, integration and other costs of $5 million directly related to the acquisition were incurred during the three and six months ended June 30, 2015, which 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. See Note 6 in Talen Energy's 2015 Form 10-K for additional information on the June 2015 acquisition of RJS Power. Divestitures Ironwood, C.P. Crane, Holtwood and Lake Wallenpaupack Power Plants In February 2016, Talen Generation completed the sale of Talen Ironwood Holdings, LLC, which through its subsidiaries owned and operated the Ironwood natural gas combined-cycle plant in Pennsylvania, for $657 million . Talen Energy recorded a pre-tax gain, net of transaction costs including the make-whole premium on the debt as described in Note 6 , of $148 million for the six months ended June 30, 2016 , which is recorded to "(Gain) loss on sale" on the Statement of Income. Proceeds from the sale of Talen Ironwood Holdings, LLC were used to repay the majority of Talen Energy's then outstanding short-term debt. At December 31, 2015, Talen Ironwood Holdings, LLC was considered an individually significant component of Talen Energy whose pre-tax income (loss) for the six months ended June 30, 2016 was $4 million and for the three and six months ended June 30, 2015 was $15 million and $33 million . See Note 6 for additional information on the redemption of debt in connection with the sale. In February 2016, Raven Power Marketing LLC, a wholly owned, indirect subsidiary of Talen Energy, completed the sale of C.P. Crane LLC, which owned and operated the C.P. Crane coal-fired power plant in Maryland. For the three months ended June 30, 2016 , Talen Energy recorded an insignificant pre-tax gain on the sale resulting from a working capital adjustment and a $6 million pre-tax loss for the six months ended June 30, 2016 , which is recorded in "(Gain) loss on sale" on the Statement of Income. The loss includes transaction costs. In April 2016, Holtwood, LLC, a wholly owned, indirect subsidiary of Talen Energy, completed the sale of the Holtwood and Lake Wallenpaupack hydroelectric facilities in Pennsylvania for $859 million . Talen Energy recorded a pre-tax gain of $421 million in "(Gain) loss on sale" on the Statement of Income for the three and six months ended June 30, 2016 related to this sale. The sales mentioned above satisfied the requirement to divest certain PJM assets to comply with a December 2014 FERC order approving the combination with RJS Power. See Note 1 in Talen Energy's 2015 Form 10-K for additional information. Development Bell Bend COLA In 2008, a Talen Energy subsidiary, Bell Bend, LLC submitted a COLA to the NRC for the proposed Bell Bend nuclear generating unit (Bell Bend) to be built adjacent to the Susquehanna plant. Also in 2008, Bell Bend, LLC submitted an application for a federal loan guarantee for Bell Bend to the DOE. In February 2014, the DOE announced the first loan guarantee, which was for a nuclear project in Georgia. The DOE has stated that the $18.5 billion currently appropriated to support new nuclear projects would not likely be enough for more than three projects. Bell Bend, LLC submits quarterly application updates for Bell Bend to the DOE to remain active in the loan guarantee application process. The NRC safety review of the Bell Bend COLA was suspended in early 2014 due to a lack of progress by the reactor vendor with respect to its NRC design certification application, approval of which is a prerequisite to issuance of a combined license for Bell Bend. The vendor subsequently suspended the NRC review in early 2015, and has not announced when they plan to restart it. Accordingly, Talen Energy had supported the licensing process with a near term focus on obtaining the Final Environmental Impact Statement (FEIS). In April 2016, Talen Energy received notification from the NRC of the completion of its FEIS. Following receipt of the FEIS, during the second quarter of 2016, Talen Energy reassessed its alternatives with respect to Bell Bend. While the COLA remains on file with the NRC, Talen Energy determined it will no longer pursue the development of the COLA. In making this decision, Talen Energy considered the following factors: forecasted energy and capacity prices; operating costs; lack of government incentives for new nuclear generation; continually rising nuclear plant construction costs; and the lack of progress by Talen Energy's current nuclear reactor vendor with respect to its NRC design certification process. Talen Energy concluded that these factors resulted in a triggering event requiring the COLA, a definite lived intangible asset, to be tested for impairment. Based on its evaluation, management determined that the amounts capitalized for the COLA are not recoverable. Management used a market approach to estimate the fair value of the incomplete COLA, considering the highest and best use from a market participant perspective, and concluded that there was no value to another market participant given the factors management utilized in making the decision to no longer pursue the COLA and the lack of usefulness to a standalone market participant. As a result, for the three and six months ended June 30, 2016 , Talen Energy recorded a pre-tax impairment charge of $204 million to the East segment that is reflected in "Impairments" on the 2016 Statements of Income. The impairment charge represents all of the COLA costs reflected on the Balance Sheet. At December 31, 2015, $201 million of costs, which included capitalized interest, associated with the licensing application were capitalized and were included on the Balance Sheets in noncurrent "Other intangibles." Montour Co-firing Project In June 2016, Talen Energy announced it plans to make modifications to its Montour coal-fired generating facility, which will enable it to co-fire using natural gas during periods of low natural gas prices. The estimated capital expenditure for plant modifications is approximately $70 million . Based on obtaining all necessary permitting and regulatory approval, the anticipated completion date is the second quarter of 2018. An insignificant amount of costs were recorded in "Construction work in progress" on the Balance Sheet at June 30, 2016.

Defined Benefits

Defined Benefits	6 Months Ended
	Jun. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Defined Benefits	Defined Benefits The table below provides the components of net periodic defined benefit costs for Talen Energy pension plans for the periods ended June 30 , for which the 2015 periods include one month of costs under the new Talen Energy pension plan. The net periodic defined benefit costs for Talen Energy's other postretirement benefit plans for the three and six months ended June 30, 2016 and 2015 were insignificant. Pension Benefits Three Months Six Months 2016 2015 2016 2015 Service cost $ 11 $ 6 $ 21 $ 7 Interest cost 18 8 37 10 Expected return on plan assets (23 ) (11 ) (46 ) (14 ) Amortization of: Actuarial (gain) loss 5 2 10 3 Net periodic defined benefit costs (credits) $ 11 $ 5 $ 22 $ 6 For the three and six months ended June 30, 2015 , Talen Energy Supply was also allocated $7 million and $18 million of costs of defined benefit plans sponsored by PPL Services based on Talen Energy Supply's participation in those plans prior to the spinoff, which management believes were reasonable at the time. Separation Benefits In 2016, Talen Energy identified approximately 85 management positions to be eliminated. As a result, Talen Energy recorded a charge of $9 million ( $5 million after tax) for the three and six months ended June 30, 2016 to "Operation and maintenance" on the Statement of Income. The charges consisted primarily of benefits under Talen Energy's severance benefits plan. At June 30, 2016 , $7 million is reflected in "Other current liabilities" on the Balance Sheet. Management continues to review its staffing levels to determine if additional eliminations are necessary. In July 2016, Talen Energy gave notice to Local Union No. 1600 of the International Brotherhood of Electrical Workers (Local 1600) of its intent to eliminate approximately 130 bargaining unit positions at the Susquehanna, Montour, and Brunner Island plants and at Talen Energy's headquarters. Talen Energy and Local 1600 are in the process of identifying impacted employees, some of whom may be eligible to receive enhanced pension and severance benefits in accordance with the terms of the collective bargaining agreement. Talen Energy expects to record a charge related to the elimination of a majority of these positions in the second half of 2016, which is not currently estimable.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Matters Talen Energy is involved in the following legal proceedings, claims and litigation. 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, Talen Energy cannot provide 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. As a result, any losses actually incurred could be substantial. 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 magistrate judge entered an order on the parties' motions for summary judgment on December 31, 2015. The judgment dismissed two of the plaintiffs' four remaining claims and provided more preferable legal standards for the remaining two claims. The case has been bifurcated as to liability and remedy. The liability trial initially was set for May 2016 and the remedy trial, in the case of any finding of liability, was to be set at a later date. However, based on a joint motion filed by the parties, the liability trial date was stayed to allow settlement discussions to proceed. In July 2016, a proposed settlement agreement was reached that includes a commitment by the defendants to cease operations of Colstrip Units 1 and 2 on or before July 1, 2022 and liability releases for the owners of all Colstrip units, without requiring monetary payments to the plaintiffs. Apart from outright dismissal of all claims against Colstrip Units 3 and 4, those units are not affected by the proposed settlement. The settlement agreement has been filed with the U.S. District Court, District of Montana, Billings Division, for approval; however Talen Energy cannot provide assurance that the settlement agreement will be approved or, if it is not, that these proceedings will not have a material adverse effect on Talen Energy's financial condition or results of operations. Management will continue to monitor the status of the proposed settlement and timing of the proposed shutdown of Units 1 and 2 and evaluate the plant's recoverability, which could result in an impairment charge in future periods. At June 30, 2016, the carrying value of Talen Montana's interest in the Colstrip coal-fired generation plant was approximately $94 million . 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 was 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 alleged 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 alleged that PADEP 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. In July 2016, the CBF withdrew its notice of alleged violations and intent to file suit. 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. 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. Trial was set for April 2016. However, based on a motion filed by the parties, the trial date was vacated to allow settlement discussions to proceed. In July 2016, Talen Montana and the other Colstrip owners entered into a settlement agreement that was filed with the court. Under the terms of the settlement, the Colstrip owners will convert to a "non-liquid" disposal system for CCR generated by the Unit 3 and 4 scrubbers no later than July 1, 2022. In exchange, the environmental groups agree to release the Colstrip owners from certain claims related to operation of the CCR Units and alleged groundwater contamination. This settlement is not expected to have a material adverse effect on Talen Energy's financial condition or results of operations. Montana Hydroelectric Litigation In February 2012, the U.S. Supreme Court issued a unanimous decision overturning judgments by the Montana First Judicial District Court and the Montana Supreme Court in pending litigation, which had held that the streambeds underlying the Talen Montana hydroelectric generating facilities were owned by the State of Montana and that Talen Montana owed the State of Montana compensation for its prior use of those streambeds. The case was remanded by the U.S. Supreme Court to the Montana Supreme Court for further proceedings in accordance with the decision and, in April 2012, was similarly remanded by the Montana Supreme Court to the Montana First Judicial District Court. In the interim, nothing further was done by the State of Montana to formally prosecute the action until April 2016, when the State filed a Complaint on Remand against Talen Montana and NorthWestern Corporation, the latter of which had purchased the facilities from Talen Montana in November 2014. The allegations of the complaint are very similar to the claims made by the State in the prior state court litigation. NorthWestern Corporation and Talen Montana have since removed the case to the Federal District Court in Montana and have filed motions to dismiss certain of the claims. The State opposed removal and filed a motion to remand the case to the First Judicial District Court. Further proceedings have not been scheduled by the federal court and, as a result, Talen Energy cannot estimate a range of reasonably possible losses, if any, related to this matter. Topaz Power Holdings, LLC (Topaz) Gas Supply Litigation In November 2014, Southwest Energy, L.P. (SWE) filed a petition alleging breach of contract against Topaz, a wholly owned indirect subsidiary of Talen Energy, in the 269 th Judicial District Court, Harris County, Texas. SWE and Topaz were parties to a natural gas supply contract that was terminated in October 2014. SWE seeks damages in the approximate amount of $7 million for Topaz's alleged failure to terminate the contract in accordance with its terms. SWE subsequently amended the petition to join additional parties, including other Talen Energy affiliates, and assert additional claims relating to the contract termination and the circumstances under which Topaz obtained an alternative natural gas supply for 2015. In April 2016, the court granted SWE's motion for partial summary judgment on the breach of contract claim, holding that the contract had not been properly terminated and as a result, Talen Energy recorded an insignificant charge to "Operation and maintenance" on the Statement of Income for the six months ended June 30, 2016. Further proceedings are required to determine SWE's damages on the breach of contract claim and Talen Energy's liability and damages, if any, on SWE's other claims in the litigation. Talen Energy continues to believe that all of SWE's claims are without merit and unsupported by the facts and law, and it intends to vigorously contest each of them. Other In addition to the above matters, from time-to-time in the ordinary course of its business Talen Energy may be subject to other legal proceedings, claims and litigation. While the outcome of these legal proceedings, claims and litigation 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. Regulatory Matters Talen Energy is subject to regulation by federal and state agencies in the various regions where it conducts business, including with respect to the following matters. 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. In April 2016, in light of the decision in the Maryland case described below, the U.S. Supreme Court denied all petitions for certiorari, allowing the Third Circuit's decision to become final. Maryland Capacity Order In April 2012, the Maryland Public Service Commission (MD PSC) ordered (the 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 (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. In April 2016, the U.S. Supreme Court issued a unanimous decision affirming the Fourth Circuit's decision and finding that Maryland's program is preempted by the Federal Power Act because it sets an interstate wholesale rate, contravening the Federal Power Act's division of authority between state and federal regulators. 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 the 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 December 2015, the United States Court of Appeals for the Ninth Circuit affirmed the FERC's October 2011 order setting out the remand process that the FERC has followed from 2011 to the present. In July 2012, Talen Montana and the City of Tacoma, one of the two parties claiming refunds at the 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, and in January 2016 the FERC denied requests for a rehearing of its order affirming the ALJ's decision. In February 2016, the City of Seattle appealed the FERC's decision to the United States Court of Appeals for the Ninth Circuit. 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 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 self-reports potential violations of certain applicable reliability requirements and submits 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. Other In addition to the regulatory matters discussed above, Talen Energy and its subsidiaries are party to other regulatory proceedings arising in the ordinary course of business or have other regulatory exposure. While the outcome of these other 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. Environmental Matters Environmental Laws and Regulations Extensive federal, state and local environmental laws and regulations are applicable to Talen Energy's air emissions, water discharges and the management of hazardous and solid waste, as well as other aspects of its business. In addition, many of these environmental considerations are also applicable to the operations of key suppliers, or customers, such as coal producers and industrial power users, and may impact the cost for their products or their demand for Talen Energy's services. 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 imposed by regulatory bodies, courts or environmental groups. Talen Energy may incur costs to comply with environmental laws and regulations, including increased capital expenditures or operating and maintenance expenses, monetary fines, penalties or other restrictions, which could be material. Legal challenges to environmental permits or rules add to the uncertainty of estimating the future cost of complying with these permits and rules. In addition, costs may increase significantly if the requirements or scope of environmental laws or regulations, or similar rules, are expanded or changed. Other From time-to-time, in the ordinary course of its business, Talen Energy may become involved in other environmental matters or become subject to other environmental statutes, regulations or requirements. In the opinion of management, based upon information currently available to Talen Energy, while the outcome of these other 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. Other Commitments and Contingencies Nuclear Insurance The Price-Anderson Act is a United States Federal law which governs liability-related issues and ensures the availability of funds for public liability claims arising from an incident at any of the U.S. licensed nuclear facilities. It also seeks to limit the liability of nuclear reactor owners for such claims from any single incident. At June 30, 2016 , the liability limit per incident is $13.4 billion for such claims, which is funded by insurance coverage from American Nuclear Insurers and an industry retroactive assessment program. Under the industry retroactive assessment program, in the event of a nuclear incident at any of the reactors covered by The Price-Anderson Act, as amended, Susquehanna Nuclear could be assessed deferred premiums of up to $255 million per incident, payable at a maximum of $38 million per year. Additionally, Susquehanna Nuclear purchases property insurance programs from NEIL, an industry mutual insurance company of which Susquehanna Nuclear is a member. At June 30, 2016 , facilities at the Susquehanna plant are insured against property damage losses up to $2.0 billion . Susquehanna Nuclear also purchases an insurance program that provides coverage for the cost of replacement power during prolonged outages of nuclear units caused by certain specified conditions. Under the NEIL property and replacement power insurance programs, Susquehanna Nuclear could be assessed retrospective premiums in the event of the insurers' adverse loss experience. This maximum assessment is $61 million at June 30, 2016 . Talen Energy has additional coverage that, under certain conditions, may reduce this exposure. Guarantees and Other Assurances In the normal course of business, Talen Energy enters into agreements that provide financial performance assurance to third parties on behalf of certain subsidiaries. Such agreements include, for example, guarantees, stand-by letters of credit issued by financial institutions and surety bonds issued by insurance companies. These agreements are entered into primarily to support or enhance the creditworthiness attributed to a subsidiary on a stand-alone basis or to facilitate the commercial activities in which these subsidiaries engage. The table below details guarantees provided as of June 30, 2016 . "Exposure" represents the estimated maximum potential amount of future payments that could be required to be made under the guarantee. The probability of expected payment/performance for the guarantees described below is remote. There was no recorded liability at June 30, 2016 or December 31, 2015 . Talen Energy Supply has indemnifications related to sales of assets that are governed by the specific sales agreement and include breach of the representations, warranties and covenants, and liabilities for certain other matters. Talen Energy's maximum exposure with respect to certain indemnifications and the expiration of the indemnifications cannot be estimated because the maximum potential liability is not always capped by the transaction documents and the expiration date is based on the applicable statute of limitations. The exposure and expiration date noted is based on those cases in which the agreements provide for specific limits. Talen Energy's exposure and related expiration dates are: Exposure at Expiration Date Indemnifications for sales of assets $ 2,796 2025 - 2036 In connection with the acquisition of RJS Power and the spinoff from PPL, Talen Energy Supply agreed to indemnify PPL and its affiliates following the spinoff for liabilities primarily relating to the Talen Energy Supply business prior to the spinoff, as well as for losses arising out of breaches of Talen Energy's failure to perform covenants and agreements in the transaction agreements following the spinoff or arising out of breaches by the Riverstone Holders of certain representations and warranties in the transaction agreements. Talen Energy Supply also agreed to indemnify PPL for liabilities relating to the employment or termination of service of PPL employees who primarily supported the Talen Energy Supply business prior to the spinoff (excluding however defined benefit pension obligations of PPL employees who terminated service prior to July 1, 2000 or who were not employed by Talen Energy Supply or its subsidiaries at the time of termination). Talen Energy Supply also agreed to indemnify PPL from tax liabilities resulting from actions by Talen Energy following the closing resulting in the transaction failing to qualify for its intended tax-free treatment. Talen Energy and/or its subsidiaries provide other miscellaneous guarantees through contracts entered into in the normal course of business. These guarantees are primarily in the form of indemnification or warranties related to services or equipment and vary in duration. The amounts of these guarantees often are not explicitly stated, and the overall maximum amount of the obligation under such guarantees cannot be reasonably estimated. Historically, no significant payments have been made with respect to these types of guarantees and the probability of payment/performance under these guarantees is remote. Talen Energy, on behalf of itself and certain of its subsidiaries, maintains insurance that may cover liability assumed under contract for bodily injury and property damage. The coverage provides maximum aggregate coverage of $100 million . This insurance may be applicable to obligations under certain of these contractual arrangements.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2016
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Prior to the spinoff, PPL Services was an affiliate of Talen Energy. The disclosures below, related to PPL Services, provide information regarding transactions that occurred prior to June 1, 2015. After June 1, 2015, transactions with PPL Services, or any other PPL subsidiaries are not related party transactions. 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, which methodology Talen Energy believes was reasonable. Talen Energy Supply was charged, primarily by PPL Services, $18 million and $67 million for the three and six months ended June 30, 2015, including amounts applied to accounts that are further distributed between capital and expense. Gas Supply Contract A subsidiary of Jade has gas supply contracts 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 periods ended June 30, Talen Energy incurred the costs reflected below for these gas purchases, which are primarily recorded in "Fuel and energy purchases" on the Statement of Income. Three Months Six Months 2016 2015 2016 2015 $ 11 $ 6 $ 21 $ 6 Other See Notes 5 and 9 for information regarding intercompany allocations prior to the spinoff associated with income taxes and defined benefits.

Other Income (Expense) - net

Other Income (Expense) - net	6 Months Ended
	Jun. 30, 2016
Other Nonoperating Income (Expense) [Abstract]
Other Income (Expense) - net	Other Income (Expense) - net Talen Energy's "Other Income (Expense) - net" for the three and six months ended June 30, 2016 and 2015 was primarily earnings on securities in NDT funds.

Fair Value Measurements and Cre

Fair Value Measurements and Credit Concentration	6 Months Ended
	Jun. 30, 2016
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 six months ended June 30, 2016 and 2015 , there were no transfers between Level 1 and Level 2. See Note 1 in Talen Energy's 2015 Form 10-K for information on the levels in the fair value hierarchy. Recurring Fair Value Measurements The assets and liabilities measured at fair value were: June 30, 2016 December 31, 2015 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 1,091 $ 1,091 $ — $ — $ 141 $ 141 $ — $ — Restricted cash and cash equivalents (a) 53 53 — — 106 106 — — Price risk management assets: Energy commodities 582 — 548 34 693 — 597 96 Total price risk management assets 582 — 548 34 693 — 597 96 NDT funds: Cash and cash equivalents 4 4 — — 11 11 — — Equity securities U.S. large-cap 637 472 165 — 616 457 159 — U.S. mid/small-cap 90 38 52 — 87 37 50 — Debt securities U.S. Treasury 112 112 — — 98 98 — — U.S. government sponsored agency 4 — 4 — 6 — 6 — Municipality 88 — 88 — 83 — 83 — Investment-grade corporate 45 — 45 — 47 — 47 — Other 1 — 1 — 3 — 3 — Receivables (payables), net 3 — 3 — — (2 ) 2 — Total NDT funds 984 626 358 — 951 601 350 — Auction rate securities (b) 6 — — 6 6 — — 6 Total assets $ 2,716 $ 1,770 $ 906 $ 40 $ 1,897 $ 848 $ 947 $ 102 Liabilities Price risk management liabilities: Energy commodities $ 520 $ — $ 498 $ 22 $ 539 $ — $ 497 $ 42 Total price risk management liabilities $ 520 $ — $ 498 $ 22 $ 539 $ — $ 497 $ 42 (a) Current portion is included in "Restricted cash and cash equivalents" and long-term portion, when applicable, 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 June 30, 2016 is as follows: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Three Months Six Months Energy Commodities, net Auction Rate Securities Total Energy Commodities, net Auction Rate Securities Total Balance at beginning of period $ 68 $ 6 $ 74 $ 54 $ 6 $ 60 Total realized/unrealized gains (losses) included in earnings (38 ) — (38 ) 22 — 22 Settlements (22 ) — (22 ) (67 ) — (67 ) Transfers into Level 3 — — — 1 — 1 Transfers out of Level 3 4 — 4 2 — 2 Balance at end of period $ 12 $ 6 $ 18 $ 12 $ 6 $ 18 A reconciliation of net assets and liabilities classified as Level 3 for the periods ended June 30, 2015 is as follows: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Three Months Six Months Energy Commodities, net Auction Rate Securities Total Energy Commodities, net Auction Rate Securities Total Balance at beginning of period $ 129 $ 8 $ 137 $ 111 $ 8 $ 119 Total realized/unrealized gains (losses) included in earnings (124 ) — (124 ) (141 ) — (141 ) Purchases (39 ) — (39 ) (39 ) — (39 ) Sales 65 (1 ) 64 65 (1 ) 64 Settlements (27 ) — (27 ) 3 — 3 Transfers into Level 3 6 — 6 10 — 10 Transfers out of Level 3 — — — 1 — 1 Balance at end of period $ 10 $ 7 $ 17 $ 10 $ 7 $ 17 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: June 30, 2016 Fair Value, net Asset (Liability) Valuation Technique Significant Unobservable Input(s) Range (Weighted Average) (a) Energy commodities Natural gas contracts (b) $ 19 Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (67%) Power sales contracts (c) (6 ) Discounted cash flow Proprietary model used to calculate forward prices 100% (100%) FTR purchase contracts (d) 1 Discounted cash flow Historical settled prices used to model forward prices 100% (100%) CRR purchase contracts (d) (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 40% (40%) December 31, 2015 Fair Value, net Asset (Liability) Valuation Technique Significant Unobservable Range (Weighted Average) (a) Energy commodities Natural gas contracts (b) $ 55 Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (50%) Power sales contracts (c) 13 Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (100%) FTR purchase contracts (d) (2 ) Discounted cash flow Historical settled prices used to model forward prices 100% (100%) Heat rate call options (e) (10 ) Discounted cash flow Proprietary model used to calculate forward prices 100% (100%) CRR purchase contracts (d) (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 46% - 47% (46.5%) (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). Net gains and losses on assets and liabilities classified as Level 3 and included in earnings for the periods ended June 30 are reported in the Statements of Income as follows: Three Months Energy Commodities, net Wholesale Energy Retail Energy Fuel and Energy Purchases 2016 2015 2016 2015 2016 2015 Total gains (losses) included in earnings $ (10 ) $ (131 ) $ (27 ) $ 8 $ (1 ) $ (1 ) Change in unrealized gains (losses) relating (9 ) (36 ) (20 ) 7 1 (4 ) Six Months Energy Commodities, net Wholesale Energy Retail Energy Fuel and Energy Purchases 2016 2015 2016 2015 2016 2015 Total gains (losses) included in earnings $ 31 $ (110 ) $ (9 ) $ (32 ) $ — $ 1 Change in unrealized gains (losses) relating (4 ) (42 ) (16 ) — — (4 ) 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 2016 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 June 30, 2016 resulting in impairments: Carrying Fair Value Measurements Using Pre-tax Loss (b) Bell Bend COLA (June 30, 2016) $ 204 $ — $ 204 Harquahala plant (June 30, 2016) 9 — 9 (a) Represents carrying value before fair value measurement. (b) The losses are 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 at June 30, 2016 are as follows: Fair Value, net Valuation Significant Range Bell Bend COLA $ — Market approach Described below 100% (100%) Harquahala plant — Discounted cash flow Proprietary model to calculate value 100% (100%) (a) The range and weighted average represent the percentage of fair value derived from the unobservable inputs. Bell Bend COLA After receiving the Final Environmental Impact Statement in the second quarter of 2016, Talen Energy reassessed its options with respect to the Bell Bend project and decided it will no longer pursue the development of the COLA. Management concluded that the amounts capitalized for the COLA are not recoverable. Management used a market approach to estimate the fair value of the incomplete COLA, considering the highest and best use from a market participant perspective, and concluded that there was no value to another market participant given current and forecasted capacity and energy prices and forecasted operating costs combined with the high cost to build a nuclear facility, as well as the lack of progress by the COLA specified nuclear reactor vendor on its NRC design certification and lack of usefulness to a standalone market participant. The COLA was valued by Talen Energy's financial department. Through this analysis, Talen Energy determined the fair value of the COLA to be negligible. Accounting personnel interpreted the analysis to appropriately classify the fair value measurement in the fair value hierarchy. See Note 8 for additional information. Harquahala Upon acquisition of the MACH Gen assets in November 2015, Talen Energy assigned no value to the plant and equipment of the Harquahala plant. Talen Energy determined that the cash flows of the plant are not recoverable and for the three and six months ended June 30, 2016, recorded an impairment charge for all amounts capitalized since acquisition. To estimate cash flows of the Harquahala plant, 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 forward energy price curves, forecasted generation, and forecasted operation, maintenance and capital expenditures and a market participant discount rate. The analysis was performed by Talen Energy's financial department. Accounting personnel interpreted the analysis to appropriately classify the fair value measurement in the fair value hierarchy. All future amounts capitalized are expected to be impaired until the carrying value of the plant is recoverable. 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 of fixed rate debt was primarily 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. The carrying amounts of borrowings under New MACH Gen's RCF and Term Loan B approximate fair value due to the variable interest rates associated with the debt. Long-term debt is primarily classified as Level 2. June 30, 2016 December 31, 2015 Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt $ 3,901 $ 3,458 $ 4,186 $ 3,343 The carrying amount of short-term debt, when outstanding, approximates fair value due to the variable interest rates associated with the 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 procedures used to manage credit risk, including master netting arrangements and collateral requirements. At June 30, 2016 , Talen Energy had credit exposure of $425 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 $265 million . The top ten counterparties, including their affiliates, accounted for $124 million , or 47% , of these exposures. Eight of these counterparties had an investment grade credit rating from S&P or Moody's and accounted for 88% of the top ten exposures. The remaining counterparties have not been rated by S&P or Moody's and are current on their obligations.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	6 Months Ended
	Jun. 30, 2016
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, 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 policy 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 procedures 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 insignificant at June 30, 2016 and there was no obligation at December 31, 2015 . Talen Energy did not post any cash collateral under master netting arrangements at June 30, 2016 and December 31, 2015 . 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. 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 2016 and 2015 , there were no active cash flow hedges and there was no hedge ineffectiveness associated with energy derivatives. At June 30, 2016 , the accumulated net unrecognized after-tax gains (losses) that are expected to be reclassified into earnings during the next 12 months were $16 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 six months ended June 30, 2016 and 2015 . 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 June 30, 2016 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 June 30 were as follows. Three Months Six Months 2016 2015 2016 2015 Operating Revenues Wholesale energy $ (194 ) $ 20 $ (134 ) $ 39 Retail energy (36 ) (9 ) (35 ) (22 ) Operating Expenses Fuel and energy purchases 84 26 101 60 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 six months ended June 30, 2016 and 2015 . Commodity Volumes At June 30, 2016 , 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 2016 (b) 2017 2018 Thereafter Power MWh (21,987,241 ) (24,721,341 ) (7,568,633 ) (719,594 ) Capacity MW-Month (3,050 ) (3,750 ) (3,746 ) (1,559 ) Gas MMBtu 87,035,186 29,084,926 16,333,048 3,206,105 FTRs MW-Month 7,212 2,929 — — Oil Barrels 33,655 — — — CRRs MWh 1,138,739 641,989 — — Emission Allowances Tons 3,322,531 (97,548 ) — — (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. Talen Energy has many physical and financial commodity purchases and sales contracts that economically hedge commodity price risk. Certain of the economic hedging strategies employed by Talen Energy utilize a combination of financial purchases and sales contracts. 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 contracts based upon their economic hedging strategy. Generation revenue hedge strategies are recorded in "Wholesale energy" on the Statements of Income. Retail sales strategies are recorded in "Retail energy" on the Statements of Income. Gas, oil and coal generation supply strategies and non-generation power and fuel supply strategies are recorded in "Fuel and energy purchases" on the Statements of Income. Certain Talen Energy subsidiaries participate in RTOs and ISOs. Talen Energy accounts for these transactions on a net hourly basis because the transactions are settled on a net hourly basis. Talen Energy records realized hourly net sales or purchases of physical power with RTOs and ISOs in its Statements of Income as "Wholesale energy" if in a net sales position and "Fuel and energy purchases" if in a net purchase position. See Notes 1 and 15 in Talen Energy's 2015 Form 10-K 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. June 30, 2016 December 31, 2015 Assets Liabilities Assets Liabilities Current: Price Risk Management Assets/Liabilities $ 429 $ 393 $ 562 $ 431 Noncurrent: Price Risk Management Assets/Liabilities 153 127 131 108 Total derivatives $ 582 $ 520 $ 693 $ 539 The following tables present the pre-tax effect of derivative instruments recognized in income for the periods ended June 30, 2016 . Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Derivative Relationships Location of Gain (Loss) Recognized in Income on Derivative Three Months Six Months Cash Flow Hedges: Commodity contracts Wholesale energy $ (1 ) $ (4 ) Fuel and energy purchases 7 15 Depreciation 1 1 Total $ 7 $ 12 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative Three Months Six Months Commodity contracts Wholesale energy $ (75 ) $ 172 Retail energy (22 ) (3 ) Fuel and energy purchases 33 (28 ) Total $ (64 ) $ 141 The following tables present the pre-tax effect of derivative instruments recognized in income for the periods ended June 30, 2015 . Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Derivative Relationships Location of Gain (Loss) Recognized in Income on Derivative Three Months Six Months Cash Flow Hedges: Commodity contracts Wholesale energy $ 2 $ — Fuel and energy purchases 8 16 Depreciation — 1 Total $ 10 $ 17 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative Three Months Six Months Commodity contracts Wholesale energy $ 138 $ 54 Retail energy 8 (31 ) Fuel and energy purchases (56 ) (8 ) Total $ 90 $ 15 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 offset 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 June 30, 2016 $ 582 $ 428 $ 16 $ 138 $ 520 $ 428 $ 9 $ 83 December 31, 2015 $ 693 $ 437 $ 74 $ 182 $ 539 $ 437 $ 30 $ 72 Credit Risk-Related Contingent Features Certain derivative contracts contain credit risk-related contingent features which, when Talen Energy is in a net liability position, would permit the counterparties to require the transfer of additional collateral upon a decrease in the credit ratings of Talen Energy. Most of these features would require the transfer of additional collateral or permit the counterparty to terminate the contract if the applicable credit rating were to fall below investment grade. Some of these features also would allow the counterparty to require additional collateral upon each downgrade in the credit rating at levels that remain above investment grade. In either case, if the credit rating were to fall below investment grade, 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. 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 June 30, 2016 , the value of derivative contracts in a net liability position that contain credit risk-related contingent features was $81 million . Collateral posted on those positions was $89 million , and the additional potential collateral requirements, primarily related to further adequate assurance features, were $7 million , which is net of receivables and payables already recorded on the Balance Sheet.

Asset Retirement Obligations

Asset Retirement Obligations	6 Months Ended
	Jun. 30, 2016
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, 2015 $ 501 Accretion expense 19 Changes in estimate of cash flow or settlement date (4 ) Obligations settled (5 ) Balance at June 30, 2016 $ 511 Substantially all of the ARO balances are classified as noncurrent at June 30, 2016 and December 31, 2015 . Talen Energy's most significant ARO recorded relates to the decommissioning of the Susquehanna nuclear plant. See Notes 13 and 16 for additional information on the assets in the NDT funds that are legally restricted for the purposes of settling this ARO.

NDT Funds

NDT Funds	6 Months Ended
	Jun. 30, 2016
Available-for-sale Securities [Abstract]
NDT Funds	NDT Funds Securities held by Talen Energy's NDT funds are classified as available-for-sale. 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. June 30, 2016 December 31, 2015 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 $ 4 $ — $ — $ 4 $ 11 $ — $ — $ 11 Equity securities 310 417 — 727 297 406 — 703 Debt securities 235 15 — 250 230 7 — 237 Receivables/payables, net 3 — — 3 — — — — Total NDT funds $ 552 $ 432 $ — $ 984 $ 538 $ 413 $ — $ 951 See Note 13 for details on the securities held by the NDT funds. There were no securities with credit losses at June 30, 2016 and December 31, 2015 . The following table shows the scheduled maturity dates of debt securities held at June 30, 2016 . Maturity Less Than 1 Year Maturity 1-5 Years Maturity 6-10 Years Maturity in Excess of 10 Years Total Amortized cost $ 8 $ 103 $ 73 $ 51 $ 235 Fair value 8 106 77 59 250 The following table shows proceeds from and realized gains and losses on sales of available-for-sale securities for the periods ended June 30 . Three Months Six Months 2016 2015 2016 2015 Proceeds from sales of NDT securities (a) $ 38 $ 62 $ 92 $ 100 Gross realized gains (b) 11 8 17 13 Gross realized losses (b) 5 6 13 9 (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)	6 Months Ended
	Jun. 30, 2016
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 June 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, 2015 $ 194 $ 44 $ 3 $ (267 ) $ (26 ) Amounts arising during the period 11 — — — 11 Reclassifications from AOCI (2 ) (7 ) — 7 (2 ) Net OCI during the period 9 (7 ) — 7 9 June 30, 2016 $ 203 $ 37 $ 3 $ (260 ) $ (17 ) December 31, 2014 $ 202 $ 63 $ 7 $ (295 ) $ (23 ) Amounts arising during the period 1 — (3 ) 46 44 Reclassifications from AOCI (2 ) (10 ) (1 ) 9 (4 ) Net OCI during the period (1 ) (10 ) (4 ) 55 40 June 30, 2015 $ 201 $ 53 $ 3 $ (240 ) $ 17 The following table presents the gains (losses) and related income taxes for reclassifications from Talen Energy's AOCI for the periods ended June 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 Six Months Affected Line Item on the Details about AOCI 2016 2015 2016 2015 Statements of Income Available-for-sale securities $ 6 $ 2 $ 4 $ 4 Other Income (Expense) - net Income Taxes (3 ) (1 ) (2 ) (2 ) Total After-tax 3 1 2 2 Qualifying derivatives Commodity contracts (1 ) 2 (4 ) — Wholesale energy 7 8 15 16 Fuel and energy purchases 1 — 1 1 Other Total Pre-tax 7 10 12 17 Income Taxes (3 ) (4 ) (5 ) (7 ) Total After-tax 4 6 7 10 Defined benefit plans Prior service costs — 1 — 1 Net actuarial loss (6 ) (8 ) (11 ) (15 ) Total Pre-tax (6 ) (7 ) (11 ) (14 ) Income Taxes 2 3 4 6 Total After-tax (4 ) (4 ) (7 ) (8 ) Total reclassifications during the period $ 3 $ 3 $ 2 $ 4

New Accounting Guidance Pending

New Accounting Guidance Pending Adoption	6 Months Ended
	Jun. 30, 2016
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. In March 2016, the FASB issued guidance to clarify the implementation of principal versus agent considerations, and in April 2016, the FASB issued guidance to clarify the identification of performance obligations contained within the original standard. 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 on its consolidated financial statements, 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. This guidance should be applied prospectively within the annual reporting 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 and the adoption of this guidance is not expected to have a significant impact on its consolidated financial statements. Recognition of Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued accounting guidance that affects the accounting for equity investments, financial liabilities under the fair value option, and the disclosure requirements for financial instruments. This guidance generally requires entities to measure equity investments that are not accounted for under the equity method of accounting and do not result in consolidation at fair value and recognize any changes in fair value in net income. Entities may elect to record equity investments without readily determinable fair values at cost, less impairment, adjusted for observable price changes. The impairment model for equity investments subject to this election is a single-step qualitative assessment performed each quarter. For financial liabilities measured using the fair value option, changes in fair value related to instrument-specific credit risk to be presented separately within OCI. This guidance should generally be applied prospectively for financial statements issued for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption is generally not permitted, although entities may early adopt the provision related to financial liabilities under the fair value option. Talen Energy expects to adopt this guidance effective January 1, 2018. Upon adoption, an entity will record a cumulative-effect adjustment to beginning retained earnings as of the beginning of the first reporting period in which the guidance is adopted, with the exception that the amendments related to equity securities with readily determined fair values should be applied prospectively. Talen Energy is currently assessing the impact of adopting this guidance on its consolidated financial statements, which may be significant for equity securities held in the NDT funds. Accounting for Leases In February 2016, the FASB issued accounting guidance that updates the accounting for leases. The updated guidance will require lessees to recognize assets and liabilities for the rights and obligations created by their leases with lease terms of more than 12 months. Consistent with current accounting guidance, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance (similar to the current capital lease) or an operating lease. However, unlike current accounting guidance, which requires only capital leases to be recognized on the balance sheet, the new accounting guidance will require both types of leases to be recognized on the balance sheet. The new accounting guidance also will require disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. These disclosures include qualitative and quantitative requirements, providing additional information about the amounts recorded in the financial statements. The accounting by lessors will remain largely unchanged. However, the new accounting guidance contains some targeted improvements that are intended to align, where necessary, lessor accounting with the lessee accounting model and with the updated revenue recognition guidance issued in 2014 and discussed above. This guidance is effective for annual reporting periods beginning after December 15, 2018 and interim periods within those years. Early application is permitted. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that entities may elect to apply. These practical expedients relate to the identification and classification of leases that commenced before the effective date, initial direct costs for leases that commenced before the effective date, and the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset. An entity that elects to apply the practical expedients will, in effect, continue to account for leases that commence before the effective date in accordance with previous accounting guidance unless the lease is modified, except that lessees are required to recognize a right-of-use asset and a lease liability for all operating leases at each reporting date based on the present value of the remaining minimum rental payments that were tracked and disclosed under previous accounting guidance. Talen Energy is currently assessing the impact of adopting this guidance on its consolidated financial statements and expects to adopt this guidance effective January 1, 2019. Share-Based Payment Accounting In March 2016, the FASB issued accounting guidance that changes the accounting for certain aspects of share-based payments to employees. This guidance requires the income tax effects of awards to be recognized in the income statement when the awards vest or are settled. For interim reporting purposes, excess tax benefits and tax deficiencies will be accounted for as discrete items in the period in which they occur and are excluded from the estimated annual effective tax rate. These amendments are applied prospectively. Excess tax benefits will be presented as an operating activity on the statement of cash flows, and this amendment can be applied retrospectively or prospectively. In addition, the requirement that excess tax benefits be realized before companies can recognize them will be eliminated; and this amendment will be applied using a modified retrospective transition method with a cumulative effect adjustment in retained earnings for excess tax benefits that have not previously been recognized. The guidance also requires an assessment of the realizability of any deferred tax assets it records upon adoption as a result of recognizing excess tax benefits and a valuation allowance will be recorded in retained earnings, if necessary. The guidance will increase the amount an employer can withhold to cover income taxes on awards and still qualify for the liability exception for shares used to satisfy the employer’s statutory income tax withholding obligation. The amendments related to outstanding liability awards at the date of adoption will be applied using a modified retrospective transition method, with a cumulative-effect adjustment to retained earnings. Cash paid to a tax authority when shares are withheld to satisfy its statutory income tax withholding obligation will be recorded as a financing activity on the statement of cash flows. Companies will have to elect how to account for forfeitures of share-based payments by either recognizing forfeitures of awards as they occur or estimating the number of awards expected to be forfeited and adjusting the estimate when it is likely to change, as is currently required. This election is required at the entity level using a modified retrospective transition method, with a cumulative-effect adjustment to retained earnings. This guidance is effective for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. Early adoption is permitted. Talen Energy is currently assessing the impact of adopting this guidance on its consolidated financial statements and expects to adopt this guidance effective January 1, 2017. Accounting for Credit Losses on Financial Instruments In June 2016, the FASB issued accounting guidance that changes the impairment model for most financial assets and certain other instruments. The standard will replace today's incurred loss approach with an expected loss model for instruments measured at amortized cost and will require allowances for available-for-sale debt securities rather than reduce the carry amount, as they do today under the other-than-temporary impairment model. The guidance will also simplify the accounting model for purchased credit-impaired debt securities and loans. The new expected credit loss model will apply to most financial assets measured at amortized cost and certain other instruments, including trade and other receivables, loans, held-to-maturity debt securities, net investments in leases and off-balance-sheet credit exposures. The existing loss contingency model will apply to instruments outside the scope of these models. The guidance also eliminates today's accounting model for purchased credit impaired loans and debt securities. Instead, the initial amortized cost for purchased assets will equal the purchase price plus the estimated allowance for credit loss at the date of acquisition. The new expected credit loss model requires an estimate of expected credit loss to be made and recorded as an allowance. When deducted from the amortized cost basis of the financial asset, it will present the net amount expected to be collected on the financial asset. An expected credit loss estimate should be based on the asset's amortized cost, reflect losses expected over the remaining contractual life, consider available information about collectability of cash flows, and reflect the risk of loss even when remote. The amendment to the impairment model for available-for-sale debt securities will measure credit losses in a manner similar to current guidance, except that losses will be recognized as allowances rather than reductions in the amortized cost of securities. This will result in a remeasurement of credit losses on available-for-sale debt securities in each reporting period. This guidance is effective for fiscal years beginning after December 15, 2019, and interim periods therein. The guidance's provisions will be applied as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. Early adoption is permitted for annual periods beginning after December 15, 2018. Talen Energy is currently assessing the impact of adopting this guidance on its consolidated financial statements and expects to adopt this guidance effective January 1, 2020.

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation 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, 2015 are derived from Talen Energy's 2015 audited Balance Sheet. The financial statements and notes thereto should be read in conjunction with the financial statements and notes contained in Talen Energy's 2015 Form 10-K. The results of operations for the three and six months ended June 30, 2016 are not necessarily indicative of the results to be expected for the full year ending December 31, 2016 or other future periods, because results for interim periods can be disproportionately influenced by various factors, developments and seasonal variations. Talen Energy Supply is considered the accounting predecessor of Talen Energy Corporation. Therefore, the financial information prior to the June 2015 spinoff 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 six months of legacy Talen Energy Supply information consolidated with one month of RJS information from June 1, 2015. Talen Energy completed the acquisition of MACH Gen in November 2015. MACH Gen's operating results for the three and six months ended June 30, 2016 are included in Talen Energy's results of operations with no comparable amounts for the same period in 2015. The assets and liabilities related to the Holtwood, Lake Wallenpaupack, C.P. Crane and Ironwood facilities were classified as "Assets held for sale" and "Liabilities held for sale" at December 31, 2015. See Note 8 for additional information on these divestitures. The sales of Talen Ironwood Holdings, LLC and C.P. Crane LLC were completed in February 2016 and the sale of the Holtwood and Lake Wallenpaupack hydroelectric facilities was completed in April 2016. The sales satisfied the requirement to divest certain PJM assets to comply with a December 2014 FERC order approving the combination with RJS Power. The classification of certain prior period amounts has been changed to conform to the presentation in the June 30, 2016 financial statements as discussed below.
New Accounting Guidance	Simplifying the Presentation of Debt Issuance Costs Effective January 1, 2016, Talen Energy adopted accounting guidance that simplifies 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. The initial adoption of this guidance required Talen Energy to reclassify long-term debt issuance costs on the Balance Sheet from assets to long-term debt. During the first quarter of 2016, Talen Energy retrospectively adopted this guidance. The December 31, 2015 Balance Sheet reflects a reclassification of $17 million between "Other noncurrent assets" and "Long-term debt" for the implementation. Issuance costs related to line-of-credit arrangements remain deferred as a long-term asset and amortized over the life of the arrangement. Accounting for Cloud Computing Arrangements Effective January 1, 2016, Talen Energy prospectively adopted guidance that clarifies how to determine if a cloud computing arrangement includes a software license. If a cloud computing arrangement contains a software license, the license should be accounted for in a manner consistent with the acquisition of other software licenses. If a cloud computing arrangement does not contain a software license, the arrangement should be accounted for as a service contract. The initial adoption of this guidance did not have a significant impact on Talen Energy. Because Talen Energy may enter into cloud computing arrangements that fall within the scope of this guidance, this guidance may have an impact in future periods. 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. In March 2016, the FASB issued guidance to clarify the implementation of principal versus agent considerations, and in April 2016, the FASB issued guidance to clarify the identification of performance obligations contained within the original standard. 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 on its consolidated financial statements, 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. This guidance should be applied prospectively within the annual reporting 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 and the adoption of this guidance is not expected to have a significant impact on its consolidated financial statements. Recognition of Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued accounting guidance that affects the accounting for equity investments, financial liabilities under the fair value option, and the disclosure requirements for financial instruments. This guidance generally requires entities to measure equity investments that are not accounted for under the equity method of accounting and do not result in consolidation at fair value and recognize any changes in fair value in net income. Entities may elect to record equity investments without readily determinable fair values at cost, less impairment, adjusted for observable price changes. The impairment model for equity investments subject to this election is a single-step qualitative assessment performed each quarter. For financial liabilities measured using the fair value option, changes in fair value related to instrument-specific credit risk to be presented separately within OCI. This guidance should generally be applied prospectively for financial statements issued for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption is generally not permitted, although entities may early adopt the provision related to financial liabilities under the fair value option. Talen Energy expects to adopt this guidance effective January 1, 2018. Upon adoption, an entity will record a cumulative-effect adjustment to beginning retained earnings as of the beginning of the first reporting period in which the guidance is adopted, with the exception that the amendments related to equity securities with readily determined fair values should be applied prospectively. Talen Energy is currently assessing the impact of adopting this guidance on its consolidated financial statements, which may be significant for equity securities held in the NDT funds. Accounting for Leases In February 2016, the FASB issued accounting guidance that updates the accounting for leases. The updated guidance will require lessees to recognize assets and liabilities for the rights and obligations created by their leases with lease terms of more than 12 months. Consistent with current accounting guidance, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance (similar to the current capital lease) or an operating lease. However, unlike current accounting guidance, which requires only capital leases to be recognized on the balance sheet, the new accounting guidance will require both types of leases to be recognized on the balance sheet. The new accounting guidance also will require disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. These disclosures include qualitative and quantitative requirements, providing additional information about the amounts recorded in the financial statements. The accounting by lessors will remain largely unchanged. However, the new accounting guidance contains some targeted improvements that are intended to align, where necessary, lessor accounting with the lessee accounting model and with the updated revenue recognition guidance issued in 2014 and discussed above. This guidance is effective for annual reporting periods beginning after December 15, 2018 and interim periods within those years. Early application is permitted. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that entities may elect to apply. These practical expedients relate to the identification and classification of leases that commenced before the effective date, initial direct costs for leases that commenced before the effective date, and the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset. An entity that elects to apply the practical expedients will, in effect, continue to account for leases that commence before the effective date in accordance with previous accounting guidance unless the lease is modified, except that lessees are required to recognize a right-of-use asset and a lease liability for all operating leases at each reporting date based on the present value of the remaining minimum rental payments that were tracked and disclosed under previous accounting guidance. Talen Energy is currently assessing the impact of adopting this guidance on its consolidated financial statements and expects to adopt this guidance effective January 1, 2019. Share-Based Payment Accounting In March 2016, the FASB issued accounting guidance that changes the accounting for certain aspects of share-based payments to employees. This guidance requires the income tax effects of awards to be recognized in the income statement when the awards vest or are settled. For interim reporting purposes, excess tax benefits and tax deficiencies will be accounted for as discrete items in the period in which they occur and are excluded from the estimated annual effective tax rate. These amendments are applied prospectively. Excess tax benefits will be presented as an operating activity on the statement of cash flows, and this amendment can be applied retrospectively or prospectively. In addition, the requirement that excess tax benefits be realized before companies can recognize them will be eliminated; and this amendment will be applied using a modified retrospective transition method with a cumulative effect adjustment in retained earnings for excess tax benefits that have not previously been recognized. The guidance also requires an assessment of the realizability of any deferred tax assets it records upon adoption as a result of recognizing excess tax benefits and a valuation allowance will be recorded in retained earnings, if necessary. The guidance will increase the amount an employer can withhold to cover income taxes on awards and still qualify for the liability exception for shares used to satisfy the employer’s statutory income tax withholding obligation. The amendments related to outstanding liability awards at the date of adoption will be applied using a modified retrospective transition method, with a cumulative-effect adjustment to retained earnings. Cash paid to a tax authority when shares are withheld to satisfy its statutory income tax withholding obligation will be recorded as a financing activity on the statement of cash flows. Companies will have to elect how to account for forfeitures of share-based payments by either recognizing forfeitures of awards as they occur or estimating the number of awards expected to be forfeited and adjusting the estimate when it is likely to change, as is currently required. This election is required at the entity level using a modified retrospective transition method, with a cumulative-effect adjustment to retained earnings. This guidance is effective for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. Early adoption is permitted. Talen Energy is currently assessing the impact of adopting this guidance on its consolidated financial statements and expects to adopt this guidance effective January 1, 2017. Accounting for Credit Losses on Financial Instruments In June 2016, the FASB issued accounting guidance that changes the impairment model for most financial assets and certain other instruments. The standard will replace today's incurred loss approach with an expected loss model for instruments measured at amortized cost and will require allowances for available-for-sale debt securities rather than reduce the carry amount, as they do today under the other-than-temporary impairment model. The guidance will also simplify the accounting model for purchased credit-impaired debt securities and loans. The new expected credit loss model will apply to most financial assets measured at amortized cost and certain other instruments, including trade and other receivables, loans, held-to-maturity debt securities, net investments in leases and off-balance-sheet credit exposures. The existing loss contingency model will apply to instruments outside the scope of these models. The guidance also eliminates today's accounting model for purchased credit impaired loans and debt securities. Instead, the initial amortized cost for purchased assets will equal the purchase price plus the estimated allowance for credit loss at the date of acquisition. The new expected credit loss model requires an estimate of expected credit loss to be made and recorded as an allowance. When deducted from the amortized cost basis of the financial asset, it will present the net amount expected to be collected on the financial asset. An expected credit loss estimate should be based on the asset's amortized cost, reflect losses expected over the remaining contractual life, consider available information about collectability of cash flows, and reflect the risk of loss even when remote. The amendment to the impairment model for available-for-sale debt securities will measure credit losses in a manner similar to current guidance, except that losses will be recognized as allowances rather than reductions in the amortized cost of securities. This will result in a remeasurement of credit losses on available-for-sale debt securities in each reporting period. This guidance is effective for fiscal years beginning after December 15, 2019, and interim periods therein. The guidance's provisions will be applied as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. Early adoption is permitted for annual periods beginning after December 15, 2018. Talen Energy is currently assessing the impact of adopting this guidance on its consolidated financial statements and expects to adopt this guidance effective January 1, 2020.
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.
Investments	Securities held by Talen Energy's NDT funds are classified as available-for-sale.

Segment and Related Informati28

Segment and Related Information (Tables)	6 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Reconciliation of Segments to Consolidated	Financial data for the segments and reconciliation to consolidated results for the periods ended June 30 are: Three Months Six Months 2016 2015 2016 2015 Talen Energy Corporation - Income Statement Data Revenues from external customers (a) East $ 627 $ 895 $ 1,723 $ 1,942 West 70 53 147 97 Total $ 697 $ 948 $ 1,870 $ 2,039 Operating Income (Loss) East $ 152 $ 147 $ 544 $ 378 West (52 ) (20 ) (80 ) (21 ) Other (52 ) (92 ) (105 ) (144 ) Total $ 48 $ 35 $ 359 $ 213 Three Months Six Months 2016 2015 2016 2015 Talen Energy Supply - Income Statement Data Revenues from external customers (a) East $ 627 $ 895 $ 1,723 $ 1,942 West 70 53 147 97 Total $ 697 $ 948 $ 1,870 $ 2,039 Operating Income (Loss) East $ 152 $ 147 $ 544 $ 378 West (52 ) (20 ) (80 ) (21 ) Other (41 ) (92 ) (94 ) (144 ) Total $ 59 $ 35 $ 370 $ 213 Talen Energy Corporation Talen Energy Supply Balance Sheet Data June 30, 2016 December 31, 2015 June 30, 2016 December 31, 2015 Assets East $ 9,979 $ 11,430 $ 9,979 $ 11,430 West 1,273 1,231 1,273 1,231 Other (b) 1,151 148 1,160 148 Total Assets $ 12,403 $ 12,809 $ 12,412 $ 12,809 (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 for29

Earnings (Loss) Per Share for Talen Energy Corporation (Tables)	6 Months Ended
	Jun. 30, 2016
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 June 30 used in the EPS calculation are: Three Months Six Months 2016 2015 2016 2015 Income (Numerator) Net Income (Loss) $ (3 ) $ 26 $ 148 $ 122 Shares of Common Stock (Denominator) Weighted-average shares - Basic EPS 128,527 98,354 128,526 90,980 Add incremental non-participating securities: Share-based payment awards — 22 949 22 Weighted-average shares - Diluted EPS 128,527 98,376 129,475 91,002

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income tax provision reconciliation	Selected information regarding the income tax provision for the periods ended June 30 was as follows: Three Months Six Months 2016 2015 2016 2015 Talen Energy Corporation Income (Loss) Before Income Taxes $ (6 ) $ (17 ) $ 251 $ 132 Income Taxes $ (3 ) $ (43 ) $ 103 $ 10 Effective Tax Rate 50 % 253 % 41 % 8 % Talen Energy Supply Income (Loss) Before Income Taxes $ 5 $ (17 ) $ 262 $ 132 Income Taxes $ 1 $ (43 ) $ 107 $ 10 Effective Tax Rate 20 % 253 % 41 % 8 %

Financing Activities (Tables)

Financing Activities (Tables)	6 Months Ended
	Jun. 30, 2016
Debt Disclosure [Abstract]
Schedule of Line of Credit Facilities	The following secured revolving credit facilities were in place at: June 30, 2016 December 31, 2015 Expiration Date Capacity Borrowed Letters of Unused Capacity Borrowed Letters of Credit Issued Talen Energy Supply RCF (a) June 2020 $ 1,850 $ 350 $ 195 $ 1,305 $ 500 $ 163 New MACH Gen RCF (b) July 2021 160 108 31 21 108 31 Total Credit Facilities $ 2,010 $ 458 $ 226 $ 1,326 $ 608 $ 194 (a) The facility is syndicated and provides Talen Energy Supply the ability to make revolving cash borrowings and to request the lenders to issue up to $925 million of letters of credit, which in combination cannot exceed the capacity of the facility at any given time. The weighted average interest rate on outstanding borrowings was 2.70% and 2.67% at June 30, 2016 and December 31, 2015. The amounts borrowed are recorded as "Short-term debt" on the Balance Sheets. See Note 7 for information on expected changes to the facility capacity at the time of closing of the Merger. (b) The facility provides New MACH Gen the ability to make revolving cash borrowings and to request the lenders to issue up to $120 million of letters of credit, which in combination cannot exceed the capacity of the facility at any given time. The weighted average interest rate on outstanding borrowings was 5.42% and 5.04% at June 30, 2016 and December 31, 2015. The amounts borrowed are recorded on the Balance Sheets as "Long-term debt" at June 30, 2016 and as "Short-term debt" at December 31, 2015. The classification as current at December 31, 2015 was based on Talen Energy's intent and ability to repay outstanding borrowings within the next year.

Acquisitions, Development and32

Acquisitions, Development and Divestitures (Tables)	6 Months Ended
	Jun. 30, 2016
Acquisitions Development And Divestitures [Abstract]
Actual operating revenue and net income	Actual operating revenue and net income of RJS, since the June 1, 2015 acquisition, included in Talen Energy's results for the periods ended June 30, 2015 were: Three and Six Months Operating Revenues (a) Net Income $ 110 $ 14 (a) Operating Revenues have been adjusted to return Sapphire to continuing operations. See Note 1 for additional information on the reclassification. Pro forma information for Talen Energy for the periods ended June 30, 2015 as if the acquisition had occurred January 1, 2015, is as follows: Three Months Six Months Operating Revenues Income (Loss) After Tax from Continuing Operations Operating Revenues Income (Loss) After Tax from Continuing Operations Pro forma $ 1,056 $ 7 $ 2,378 $ 95 Basic and diluted earnings per share for Talen Energy Corporation 0.05 0.74

Defined Benefits (Tables)

Defined Benefits (Tables)	6 Months Ended
	Jun. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Schedule Of Net Periodic Defined Benefit Costs (Credits)	The table below provides the components of net periodic defined benefit costs for Talen Energy pension plans for the periods ended June 30 , for which the 2015 periods include one month of costs under the new Talen Energy pension plan. The net periodic defined benefit costs for Talen Energy's other postretirement benefit plans for the three and six months ended June 30, 2016 and 2015 were insignificant. Pension Benefits Three Months Six Months 2016 2015 2016 2015 Service cost $ 11 $ 6 $ 21 $ 7 Interest cost 18 8 37 10 Expected return on plan assets (23 ) (11 ) (46 ) (14 ) Amortization of: Actuarial (gain) loss 5 2 10 3 Net periodic defined benefit costs (credits) $ 11 $ 5 $ 22 $ 6

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Guarantees	Talen Energy's exposure and related expiration dates are: Exposure at Expiration Date Indemnifications for sales of assets $ 2,796 2025 - 2036

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2016
Related Party Transactions [Abstract]
Costs incurred for gas purchases	For the periods ended June 30, Talen Energy incurred the costs reflected below for these gas purchases, which are primarily recorded in "Fuel and energy purchases" on the Statement of Income. Three Months Six Months 2016 2015 2016 2015 $ 11 $ 6 $ 21 $ 6

Fair Value Measurements and C36

Fair Value Measurements and Credit Concentration (Tables)	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities Measured on Recurring Basis	The assets and liabilities measured at fair value were: June 30, 2016 December 31, 2015 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 1,091 $ 1,091 $ — $ — $ 141 $ 141 $ — $ — Restricted cash and cash equivalents (a) 53 53 — — 106 106 — — Price risk management assets: Energy commodities 582 — 548 34 693 — 597 96 Total price risk management assets 582 — 548 34 693 — 597 96 NDT funds: Cash and cash equivalents 4 4 — — 11 11 — — Equity securities U.S. large-cap 637 472 165 — 616 457 159 — U.S. mid/small-cap 90 38 52 — 87 37 50 — Debt securities U.S. Treasury 112 112 — — 98 98 — — U.S. government sponsored agency 4 — 4 — 6 — 6 — Municipality 88 — 88 — 83 — 83 — Investment-grade corporate 45 — 45 — 47 — 47 — Other 1 — 1 — 3 — 3 — Receivables (payables), net 3 — 3 — — (2 ) 2 — Total NDT funds 984 626 358 — 951 601 350 — Auction rate securities (b) 6 — — 6 6 — — 6 Total assets $ 2,716 $ 1,770 $ 906 $ 40 $ 1,897 $ 848 $ 947 $ 102 Liabilities Price risk management liabilities: Energy commodities $ 520 $ — $ 498 $ 22 $ 539 $ — $ 497 $ 42 Total price risk management liabilities $ 520 $ — $ 498 $ 22 $ 539 $ — $ 497 $ 42 (a) Current portion is included in "Restricted cash and cash equivalents" and long-term portion, when applicable, 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 June 30, 2016 is as follows: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Three Months Six Months Energy Commodities, net Auction Rate Securities Total Energy Commodities, net Auction Rate Securities Total Balance at beginning of period $ 68 $ 6 $ 74 $ 54 $ 6 $ 60 Total realized/unrealized gains (losses) included in earnings (38 ) — (38 ) 22 — 22 Settlements (22 ) — (22 ) (67 ) — (67 ) Transfers into Level 3 — — — 1 — 1 Transfers out of Level 3 4 — 4 2 — 2 Balance at end of period $ 12 $ 6 $ 18 $ 12 $ 6 $ 18 A reconciliation of net assets and liabilities classified as Level 3 for the periods ended June 30, 2015 is as follows: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Three Months Six Months Energy Commodities, net Auction Rate Securities Total Energy Commodities, net Auction Rate Securities Total Balance at beginning of period $ 129 $ 8 $ 137 $ 111 $ 8 $ 119 Total realized/unrealized gains (losses) included in earnings (124 ) — (124 ) (141 ) — (141 ) Purchases (39 ) — (39 ) (39 ) — (39 ) Sales 65 (1 ) 64 65 (1 ) 64 Settlements (27 ) — (27 ) 3 — 3 Transfers into Level 3 6 — 6 10 — 10 Transfers out of Level 3 — — — 1 — 1 Balance at end of period $ 10 $ 7 $ 17 $ 10 $ 7 $ 17
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: June 30, 2016 Fair Value, net Asset (Liability) Valuation Technique Significant Unobservable Input(s) Range (Weighted Average) (a) Energy commodities Natural gas contracts (b) $ 19 Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (67%) Power sales contracts (c) (6 ) Discounted cash flow Proprietary model used to calculate forward prices 100% (100%) FTR purchase contracts (d) 1 Discounted cash flow Historical settled prices used to model forward prices 100% (100%) CRR purchase contracts (d) (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 40% (40%) December 31, 2015 Fair Value, net Asset (Liability) Valuation Technique Significant Unobservable Range (Weighted Average) (a) Energy commodities Natural gas contracts (b) $ 55 Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (50%) Power sales contracts (c) 13 Discounted cash flow Proprietary model used to calculate forward prices 10% - 100% (100%) FTR purchase contracts (d) (2 ) Discounted cash flow Historical settled prices used to model forward prices 100% (100%) Heat rate call options (e) (10 ) Discounted cash flow Proprietary model used to calculate forward prices 100% (100%) CRR purchase contracts (d) (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 46% - 47% (46.5%) (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). The significant unobservable inputs used in and the quantitative information about the nonrecurring fair value measurement of assets and liabilities classified as Level 3 at June 30, 2016 are as follows: Fair Value, net Valuation Significant Range Bell Bend COLA $ — Market approach Described below 100% (100%) Harquahala plant — Discounted cash flow Proprietary model to calculate 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 June 30 are reported in the Statements of Income as follows: Three Months Energy Commodities, net Wholesale Energy Retail Energy Fuel and Energy Purchases 2016 2015 2016 2015 2016 2015 Total gains (losses) included in earnings $ (10 ) $ (131 ) $ (27 ) $ 8 $ (1 ) $ (1 ) Change in unrealized gains (losses) relating (9 ) (36 ) (20 ) 7 1 (4 ) Six Months Energy Commodities, net Wholesale Energy Retail Energy Fuel and Energy Purchases 2016 2015 2016 2015 2016 2015 Total gains (losses) included in earnings $ 31 $ (110 ) $ (9 ) $ (32 ) $ — $ 1 Change in unrealized gains (losses) relating (4 ) (42 ) (16 ) — — (4 )
Nonrecurring Fair Value Measurements	The following nonrecurring fair value measurements occurred during the periods ended June 30, 2016 resulting in impairments: Carrying Fair Value Measurements Using Pre-tax Loss (b) Bell Bend COLA (June 30, 2016) $ 204 $ — $ 204 Harquahala plant (June 30, 2016) 9 — 9 (a) Represents carrying value before fair value measurement. (b) The losses are 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 of fixed rate debt was primarily 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. The carrying amounts of borrowings under New MACH Gen's RCF and Term Loan B approximate fair value due to the variable interest rates associated with the debt. Long-term debt is primarily classified as Level 2. June 30, 2016 December 31, 2015 Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt $ 3,901 $ 3,458 $ 4,186 $ 3,343

Derivative Instruments and He37

Derivative Instruments and Hedging Activities (Tables)	6 Months Ended
	Jun. 30, 2016
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 June 30 were as follows. Three Months Six Months 2016 2015 2016 2015 Operating Revenues Wholesale energy $ (194 ) $ 20 $ (134 ) $ 39 Retail energy (36 ) (9 ) (35 ) (22 ) Operating Expenses Fuel and energy purchases 84 26 101 60
Commodity Volumes - Volumes of Derivative (Sales) Purchase Contracts	At June 30, 2016 , 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 2016 (b) 2017 2018 Thereafter Power MWh (21,987,241 ) (24,721,341 ) (7,568,633 ) (719,594 ) Capacity MW-Month (3,050 ) (3,750 ) (3,746 ) (1,559 ) Gas MMBtu 87,035,186 29,084,926 16,333,048 3,206,105 FTRs MW-Month 7,212 2,929 — — Oil Barrels 33,655 — — — CRRs MWh 1,138,739 641,989 — — Emission Allowances Tons 3,322,531 (97,548 ) — — (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. June 30, 2016 December 31, 2015 Assets Liabilities Assets Liabilities Current: Price Risk Management Assets/Liabilities $ 429 $ 393 $ 562 $ 431 Noncurrent: Price Risk Management Assets/Liabilities 153 127 131 108 Total derivatives $ 582 $ 520 $ 693 $ 539
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 June 30, 2016 . Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Derivative Relationships Location of Gain (Loss) Recognized in Income on Derivative Three Months Six Months Cash Flow Hedges: Commodity contracts Wholesale energy $ (1 ) $ (4 ) Fuel and energy purchases 7 15 Depreciation 1 1 Total $ 7 $ 12 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative Three Months Six Months Commodity contracts Wholesale energy $ (75 ) $ 172 Retail energy (22 ) (3 ) Fuel and energy purchases 33 (28 ) Total $ (64 ) $ 141 The following tables present the pre-tax effect of derivative instruments recognized in income for the periods ended June 30, 2015 . Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Derivative Relationships Location of Gain (Loss) Recognized in Income on Derivative Three Months Six Months Cash Flow Hedges: Commodity contracts Wholesale energy $ 2 $ — Fuel and energy purchases 8 16 Depreciation — 1 Total $ 10 $ 17 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative Three Months Six Months Commodity contracts Wholesale energy $ 138 $ 54 Retail energy 8 (31 ) Fuel and energy purchases (56 ) (8 ) Total $ 90 $ 15
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 June 30, 2016 $ 582 $ 428 $ 16 $ 138 $ 520 $ 428 $ 9 $ 83 December 31, 2015 $ 693 $ 437 $ 74 $ 182 $ 539 $ 437 $ 30 $ 72
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 June 30, 2016 $ 582 $ 428 $ 16 $ 138 $ 520 $ 428 $ 9 $ 83 December 31, 2015 $ 693 $ 437 $ 74 $ 182 $ 539 $ 437 $ 30 $ 72

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	6 Months Ended
	Jun. 30, 2016
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, 2015 $ 501 Accretion expense 19 Changes in estimate of cash flow or settlement date (4 ) Obligations settled (5 ) Balance at June 30, 2016 $ 511

NDT Funds (Tables)

NDT Funds (Tables)	6 Months Ended
	Jun. 30, 2016
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. June 30, 2016 December 31, 2015 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 $ 4 $ — $ — $ 4 $ 11 $ — $ — $ 11 Equity securities 310 417 — 727 297 406 — 703 Debt securities 235 15 — 250 230 7 — 237 Receivables/payables, net 3 — — 3 — — — — Total NDT funds $ 552 $ 432 $ — $ 984 $ 538 $ 413 $ — $ 951
Investments Classified by Contractual Maturity Date	The following table shows the scheduled maturity dates of debt securities held at June 30, 2016 . Maturity Less Than 1 Year Maturity 1-5 Years Maturity 6-10 Years Maturity in Excess of 10 Years Total Amortized cost $ 8 $ 103 $ 73 $ 51 $ 235 Fair value 8 106 77 59 250
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 June 30 . Three Months Six Months 2016 2015 2016 2015 Proceeds from sales of NDT securities (a) $ 38 $ 62 $ 92 $ 100 Gross realized gains (b) 11 8 17 13 Gross realized losses (b) 5 6 13 9 (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 Comprehensi40

Accumulated Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2016
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 June 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, 2015 $ 194 $ 44 $ 3 $ (267 ) $ (26 ) Amounts arising during the period 11 — — — 11 Reclassifications from AOCI (2 ) (7 ) — 7 (2 ) Net OCI during the period 9 (7 ) — 7 9 June 30, 2016 $ 203 $ 37 $ 3 $ (260 ) $ (17 ) December 31, 2014 $ 202 $ 63 $ 7 $ (295 ) $ (23 ) Amounts arising during the period 1 — (3 ) 46 44 Reclassifications from AOCI (2 ) (10 ) (1 ) 9 (4 ) Net OCI during the period (1 ) (10 ) (4 ) 55 40 June 30, 2015 $ 201 $ 53 $ 3 $ (240 ) $ 17
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 June 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 Six Months Affected Line Item on the Details about AOCI 2016 2015 2016 2015 Statements of Income Available-for-sale securities $ 6 $ 2 $ 4 $ 4 Other Income (Expense) - net Income Taxes (3 ) (1 ) (2 ) (2 ) Total After-tax 3 1 2 2 Qualifying derivatives Commodity contracts (1 ) 2 (4 ) — Wholesale energy 7 8 15 16 Fuel and energy purchases 1 — 1 1 Other Total Pre-tax 7 10 12 17 Income Taxes (3 ) (4 ) (5 ) (7 ) Total After-tax 4 6 7 10 Defined benefit plans Prior service costs — 1 — 1 Net actuarial loss (6 ) (8 ) (11 ) (15 ) Total Pre-tax (6 ) (7 ) (11 ) (14 ) Income Taxes 2 3 4 6 Total After-tax (4 ) (4 ) (7 ) (8 ) Total reclassifications during the period $ 3 $ 3 $ 2 $ 4

Business and Basis of Present41

Business and Basis of Presentation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Restructuring Cost and Reserve [Line Items]
TSA term of agreement			2 years
Retail energy	$ (189)	$ (243)	$ (448)	$ (554)
Earnings per Share Basic (in dollars per share)	$ 0.02	$ (0.26)	$ (1.15)	$ (1.34)
PPL Corporation
Restructuring Cost and Reserve [Line Items]
Services under TSA	$ 10		$ 22
Operating Expense
Restructuring Cost and Reserve [Line Items]
Prior period reclassification adjustment		$ 125		$ 20
Fuel and energy purchases
Restructuring Cost and Reserve [Line Items]
Prior period reclassification adjustment		15		33
Operating Revenues
Restructuring Cost and Reserve [Line Items]
Prior period reclassification adjustment		8		8
Operating Expenses
Restructuring Cost and Reserve [Line Items]
Prior period reclassification adjustment		(7)		(7)
Talen Energy Supply
Restructuring Cost and Reserve [Line Items]
Stock-based compensation		25		25
Retail energy	$ (189)	(243)	$ (448)	(554)
Spinoff Transaction
Restructuring Cost and Reserve [Line Items]
Restructuring costs		8		10
Restatement Adjustment | Revenue Adjustment for Affiliate Payable
Restructuring Cost and Reserve [Line Items]
Retail energy		7		7
Income (Loss) from Continuing Operations After Income Taxes		$ 4		$ 4
Earnings per Share Basic (in dollars per share)		$ 0.04		$ 0.04

Summary of Significant Accoun42

Summary of Significant Accounting Policies (Details) - New Accounting Pronouncement, Early Adoption, Effect $ in Millions	Dec. 31, 2015USD ($)
Long-term Debt
New Accounting Pronouncement, Early Adoption [Line Items]
Debt issuance costs	$ 17
Other Noncurrent Assets
New Accounting Pronouncement, Early Adoption [Line Items]
Debt issuance costs	$ (17)

Segment and Related Informati43

Segment and Related Information - Income Statement Data (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues from external customers		$ 697	$ 948	$ 1,870	$ 2,039
Operating income (loss)		48	35	359	213
Operating Segments | East
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues from external customers	[1]	627	895	1,723	1,942
Operating income (loss)		152	147	544	378
Operating Segments | West
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues from external customers	[1]	70	53	147	97
Operating income (loss)		(52)	(20)	(80)	(21)
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating income (loss)		(52)	(92)	(105)	(144)
Talen Energy Supply
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues from external customers		697	948	1,870	2,039
Operating income (loss)		59	35	370	213
Talen Energy Supply | Operating Segments | East
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues from external customers	[1]	627	895	1,723	1,942
Operating income (loss)		152	147	544	378
Talen Energy Supply | Operating Segments | West
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues from external customers	[1]	70	53	147	97
Operating income (loss)		(52)	(20)	(80)	(21)
Talen Energy Supply | Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating income (loss)		$ (41)	$ (92)	$ (94)	$ (144)
[1]	Includes unrealized gains and losses from derivatives. See Note 14 for additional information.

Segment and Related Informati44

Segment and Related Information - Balance Sheet Data (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		$ 12,403	$ 12,809
Operating Segments | East
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		9,979	11,430
Operating Segments | West
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		1,273	1,231
Other
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	[1]	1,151	148
Talen Energy Supply
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		12,412	12,809
Talen Energy Supply | Operating Segments | East
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		9,979	11,430
Talen Energy Supply | Operating Segments | West
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		1,273	1,231
Talen Energy Supply | Other
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	[1]	$ 1,160	$ 148
[1]	Primarily consists of unallocated items, including cash and PP&E.

Earnings (Loss) Per Share for45

Earnings (Loss) Per Share for Talen Energy Corporation (Details) - USD ($) $ in Millions	Jun. 01, 2015	Jun. 30, 2016	Jun. 30, 2015	May 31, 2015	Jun. 30, 2016		Jun. 30, 2015
Income (Numerator)
Net Income (Loss)		$ (3)	$ 26	$ 32	$ 148		$ 122
Shares of Common Stock (Denominator)
Weighted-average shares - Basic EPS (in shares)		128,527,000	98,354,000		128,526,000		90,980,000
Share-based payment awards (in shares)		0	22,000		949,000		22,000
Weighted-average shares - Diluted EPS (in shares)		128,527,000	98,376,000		129,475,000		91,002,000
Shares Issued (Numeric) [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)		2,305,000			1,225,000
Common Stock
Schedule of Capitalization, Equity [Line Items]
Stock issuance (shares)	128,499,023
Common stock shares issued to PPL shareholders	83,524,365				0	[1],[2]	83,524,000	[1],[2]
Common stock issued for acquisition of RJS Power, shares	44,974,658						44,975,000	[1],[2]
[1]	Shares in thousands. Each share entitles the holder to one vote on any questions presented at any stockholders' meeting.
[2]	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 in Talen Energy's Form 10-K for additional information on the spinoff. The amount in 2016 represents a correction to the June 1, 2015 predecessor member's equity for a contribution received from PPL.

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Tax Provision [Line Items]
Income (Loss) Before Income Taxes	$ (6)	$ (17)	$ 251	$ 132
Income Taxes	$ (3)	$ (43)	$ 103	$ 10
Effective Tax Rate (as a percent)	50.00%	253.00%	41.00%	8.00%
Annualized effective tax rate (as a percent)			39.87%	32.52%
Settlement of previously unrecognized tax benefits		$ 12		$ 12
State deferred tax liabilities		17		17
Talen Energy Supply
Income Tax Provision [Line Items]
Income (Loss) Before Income Taxes	$ 5	(17)	$ 262	132
Income Taxes	$ 1	$ (43)	$ 107	$ 10
Effective Tax Rate (as a percent)	20.00%	253.00%	41.00%	8.00%

Financing Activities (Revolving

Financing Activities (Revolving Credit Facilities) (Details) - USD ($)		Jun. 30, 2016	Dec. 31, 2015
Credit Arrangments and Short-term Debt
Capacity		$ 2,010,000,000
Borrowed		458,000,000	$ 608,000,000
Letters of Credit Issued		226,000,000	194,000,000
Unused Capacity		1,326,000,000
Letter of Credit | New MACH Gen Revolving Credit Facility
Credit Arrangments and Short-term Debt
Capacity		120,000,000
Letter of Credit | Talen Energy Supply | Talen Energy Supply Revolving Credit Facility
Credit Arrangments and Short-term Debt
Capacity		925,000,000
Revolving Credit Facility | New MACH Gen Revolving Credit Facility
Credit Arrangments and Short-term Debt
Capacity	[1]	160,000,000
Borrowed	[1]	108,000,000	108,000,000
Letters of Credit Issued	[1]	31,000,000	$ 31,000,000
Unused Capacity	[1]	$ 21,000,000
Weighted average interest rate (as a percent)		5.42%	5.04%
Revolving Credit Facility | Talen Energy Supply | Talen Energy Supply Revolving Credit Facility
Credit Arrangments and Short-term Debt
Capacity	[2]	$ 1,850,000,000
Borrowed	[2]	350,000,000	$ 500,000,000
Letters of Credit Issued	[2]	195,000,000	$ 163,000,000
Unused Capacity	[2]	$ 1,305,000,000
Weighted average interest rate (as a percent)		2.70%	2.67%
[1]	The facility provides New MACH Gen the ability to make revolving cash borrowings and to request the lenders to issue up to $120 million of letters of credit, which in combination cannot exceed the capacity of the facility at any given time. The weighted average interest rate on outstanding borrowings was 5.42% and 5.04% at June 30, 2016 and December 31, 2015. The amounts borrowed are recorded on the Balance Sheets as "Long-term debt" at June 30, 2016 and as "Short-term debt" at December 31, 2015. The classification as current at December 31, 2015 was based on Talen Energy's intent and ability to repay outstanding borrowings within the next year.
[2]	The facility is syndicated and provides Talen Energy Supply the ability to make revolving cash borrowings and to request the lenders to issue up to $925 million of letters of credit, which in combination cannot exceed the capacity of the facility at any given time. The weighted average interest rate on outstanding borrowings was 2.70% and 2.67% at June 30, 2016 and December 31, 2015. The amounts borrowed are recorded as "Short-term debt" on the Balance Sheets. See Note 7 for information on expected changes to the facility capacity at the time of closing of the Merger.

Financing Activities (Narrative

Financing Activities (Narrative) (Details) - USD ($)	1 Months Ended	6 Months Ended
	Jan. 31, 2016	Jun. 30, 2016	May 31, 2016	Dec. 31, 2015	May 31, 2015
Debt Instrument [Line Items]
Long-term Debt		$ 3,896,000,000		$ 3,787,000,000
Senior Unsecured Notes
Debt Instrument [Line Items]
Interest rate (as a percent)			6.20%
Debt instrument face amount			$ 350,000,000
Senior Unsecured Notes | Senior Unsecured Notes Due 2025
Debt Instrument [Line Items]
Extinguishment of debt	$ 41,000,000
Weighted average interest rate (as a percent)	8.857%
Make whole premium	$ 14,000,000
Talen Energy Supply
Debt Instrument [Line Items]
Long-term Debt		3,896,000,000		$ 3,787,000,000
Talen Energy Supply | Unsecured Debt | Redeemable Senior Unsecured Notes due 2025
Debt Instrument [Line Items]
Interest rate (as a percent)					6.50%
Talen Energy Supply | Facility Agreement
Debt Instrument [Line Items]
Potential maximum Facility Agreement capacity		$ 500,000,000
Expiration date		Jun. 30, 2017
Talen Energy Supply | Secured Trading Facility
Debt Instrument [Line Items]
Secured energy marketing and trading facility capacity		$ 1,300,000,000
Term (in years)		5 years
Renewal term		1 year
Long-term Debt		$ 63,000,000

Merger Agreement (Details)

Merger Agreement (Details) - USD ($)		Jun. 02, 2016	Aug. 05, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Business Acquisition [Line Items]
Capacity				$ 2,010,000,000		$ 2,010,000,000
Talen Energy Supply
Business Acquisition [Line Items]
Stock-based compensation					$ 25,000,000		$ 25,000,000
Talen Energy Supply Revolving Credit Facility | Revolving Credit Facility | Talen Energy Supply
Business Acquisition [Line Items]
Capacity	[1]			1,850,000,000		1,850,000,000
RJS Merger
Business Acquisition [Line Items]
Right to receive cash (in dollars per share)		$ 14
Unrestricted cash and cash equivalents and undrawn revolver capacity		$ 350,000,000
Proceeds from debt		$ 250,000,000
Merger expenses				$ 11,000,000		$ 11,000,000
RJS Merger | Riverstone Affiliates
Business Acquisition [Line Items]
Ownership percentage		35.00%
RJS Merger | Talen Energy Supply | Secured Debt
Business Acquisition [Line Items]
Debt instrument face amount		$ 250,000,000
RJS Merger | Talen Energy Corporation
Business Acquisition [Line Items]
Termination fee		50,000,000
RJS Merger | Merger Sub Inc
Business Acquisition [Line Items]
Termination fee		$ 85,000,000
RJS Merger | Scenario, Forecast
Business Acquisition [Line Items]
Stock-based compensation			$ 14,000,000
RJS Merger | Talen Energy Supply Revolving Credit Facility | Revolving Credit Facility | Scenario, Forecast | Talen Energy Supply
Business Acquisition [Line Items]
Capacity	[1]		$ 1,400,000,000
[1]	The facility is syndicated and provides Talen Energy Supply the ability to make revolving cash borrowings and to request the lenders to issue up to $925 million of letters of credit, which in combination cannot exceed the capacity of the facility at any given time. The weighted average interest rate on outstanding borrowings was 2.70% and 2.67% at June 30, 2016 and December 31, 2015. The amounts borrowed are recorded as "Short-term debt" on the Balance Sheets. See Note 7 for information on expected changes to the facility capacity at the time of closing of the Merger.

Acquisitions, Development and50

Acquisitions, Development and Divestitures (Acquisitions) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015		Jun. 30, 2015
RJS Power and MACH Gen
Business Acquisition [Line Items]
Operating Revenues	$ 1,056		$ 2,378
Income (Loss) After Tax from Continuing Operations	$ 7		$ 95
Basic earnings per share for Talen Energy Corporation (in dollars per share)	$ 0.05		$ 0.74
Diluted earnings per share for Talen Energy Corporation (in dollars per share)	$ 0.05		$ 0.74
Nonrecurring acquisition, integration and other costs	$ 5		$ 5
RJS Power
Business Acquisition [Line Items]
Operating Revenues	110	[1]	110
Net Income	$ 14		$ 14
[1]	Operating Revenues have been adjusted to return Sapphire to continuing operations. See Note 1 for additional information on the reclassification.

Acquisitions, Development and51

Acquisitions, Development and Divestitures (Divestitures) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 29, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Apr. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale		$ 423	$ 0	$ 563	$ 0
Disposal Group, Held-for-sale, Not Discontinued Operations | Talen Ironwood Holdings, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received	$ 657
Gain (loss) on sale	148
Individually significant component pretax income (loss)			$ 15	4	$ 33
Disposal Group, Held-for-sale, Not Discontinued Operations | C.P. Crane, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale	$ (6)
Disposal Group, Held-for-sale, Not Discontinued Operations | Holtwood and Lake Wallenpaupack Hydroelectric Projects
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received						$ 859
Gain (loss) on sale		$ 421		$ 421

Acquisitions, Development and52

Acquisitions, Development and Divestitures (Development) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)project	Jun. 30, 2015USD ($)
Business Acquisition [Line Items]
Maximum number of projects with current funding | project			3
Impairment charge	$ 213	$ 0	$ 213	$ 0
Proposed Bell Bend Nuclear Unit
Business Acquisition [Line Items]
Impairment charge	204		204
Capitalized costs associated with licensing efforts	201		201
Montour Co-firing Project
Business Acquisition [Line Items]
Construction In Progress, Total Project Cost	70		70
Bell Bend, LLC
Business Acquisition [Line Items]
Current appropriated federal loan guarantees for nuclear projects	$ 18,500		$ 18,500

Defined Benefits (Details)

Defined Benefits (Details) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2016position	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)management_position	Jun. 30, 2015USD ($)
Separation Benefits
Number of management positions | management_position				85
Charge		$ 9		$ 9
Charge, net of tax		5		5
Separation benefits liability		7		7
Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		11	$ 6	21	$ 7
Interest cost		18	8	37	10
Expected return on plan assets		(23)	(11)	(46)	(14)
Amortization of:
Actuarial (gain) loss		5	2	10	3
Net periodic defined benefit costs (credits)		$ 11	5	$ 22	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			$ 7		$ 18
Subsequent Event
Separation Benefits
Restructuring and Related Cost, Number of Positions Eliminated | position	130

Commitments and Contingencies54

Commitments and Contingencies (Legal Matters) (Details)	Dec. 31, 2015USD ($)claim	Dec. 31, 2015USD ($)claim	Apr. 30, 2015project	Aug. 31, 2014project	May 31, 2014project	Jul. 31, 2013project	Mar. 31, 2013USD ($)claim	Jul. 31, 2012USD ($)plaintiff	Apr. 30, 2012utility	Jun. 30, 2016USD ($)	Nov. 30, 2014USD ($)
Legal Matters - Gas Supply Litigation (Numeric) [Abstract]
Number of separate claims included in the complaint | 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		2			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	4		4
Number of plants with more preferable legal standards claims | claim	2
Carrying value of plant	$ 13,468,000,000	$ 13,468,000,000								$ 13,607,000,000
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
Colstrip Units 1 and 2
Legal Matters - Gas Supply Litigation (Numeric) [Abstract]
Carrying value of plant										94,000,000
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
Pending Litigation | Topaz Gas Supply
Legal Matters - Gas Supply Litigation (Numeric) [Abstract]
Estimate of possible loss											$ 7,000,000
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 Contingencies55

Commitments and Contingencies (Environmental Matters and Other) (Details)	Jun. 30, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
Maximum amount for public liability claims for nuclear incident	$ 13,400,000,000
Maximum amount assessed for nuclear incident	255,000,000
Maximum amount payable per year assessed for nuclear incident	38,000,000
Maximum amount of insured property damages losses coverage nuclear plant	2,000,000,000
Maximum assessment retroactive premiums insured outage loss coverage	$ 61,000,000

Commitments and Contingencies56

Commitments and Contingencies (Guarantees and Other Assurances) (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Guarantor Obligations [Line Items]
Recorded liability for all guarantees	$ 0	$ 0
Maximum aggregate coverage bodily injury and property damage	100,000,000
Indemnification Agreement | Indemnifications for sales of assets
Guarantor Obligations [Line Items]
Maximum exposure	$ 2,796,000,000

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Trailstone NA Logistic LLC | Costs for gas purchases
Related Party Transaction [Line Items]
Amount of related party transaction	$ 11	$ 6	$ 21	$ 6
Talen Energy Supply | PPL Services
Related Party Transaction [Line Items]
Support cost allocations from subsidiary of parent to registrant		$ 18		$ 67

Fair Value Measurements and C58

Fair Value Measurements and Credit Concentration (Assets and Liabilities Measured on Recurring Basis Table) (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Price risk management assets:
Gross		$ 582	$ 693
Price risk management liabilities:
Gross		520	539
Recurring
Assets
Cash and cash equivalents		1,091	141
Restricted cash and cash equivalents	[1]	53	106
Price risk management assets:
Gross		582	693
NDT funds		984	951
Total assets		2,716	1,897
Price risk management liabilities:
Gross		520	539
Recurring | Cash and cash equivalents
Price risk management assets:
NDT funds		4	11
Recurring | U.S. large-cap
Price risk management assets:
NDT funds		637	616
Recurring | U.S. mid/small-cap
Price risk management assets:
NDT funds		90	87
Recurring | U.S. Treasury
Price risk management assets:
NDT funds		112	98
Recurring | U.S. government sponsored agency
Price risk management assets:
NDT funds		4	6
Recurring | Municipality
Price risk management assets:
NDT funds		88	83
Recurring | Investment-grade corporate
Price risk management assets:
NDT funds		45	47
Recurring | Other
Price risk management assets:
NDT funds		1	3
Recurring | Receivables/payables, net
Price risk management assets:
NDT funds		3	0
Recurring | Auction Rate Securities
Price risk management assets:
Auction rate securities	[2]	6	6
Recurring | Level 1
Assets
Cash and cash equivalents		1,091	141
Restricted cash and cash equivalents	[1]	53	106
Price risk management assets:
Gross		0	0
NDT funds		626	601
Total assets		1,770	848
Price risk management liabilities:
Gross		0	0
Recurring | Level 1 | Cash and cash equivalents
Price risk management assets:
NDT funds		4	11
Recurring | Level 1 | U.S. large-cap
Price risk management assets:
NDT funds		472	457
Recurring | Level 1 | U.S. mid/small-cap
Price risk management assets:
NDT funds		38	37
Recurring | Level 1 | U.S. Treasury
Price risk management assets:
NDT funds		112	98
Recurring | Level 1 | Receivables/payables, net
Price risk management assets:
NDT funds		0	(2)
Recurring | Level 2
Price risk management assets:
Gross		548	597
NDT funds		358	350
Total assets		906	947
Price risk management liabilities:
Gross		498	497
Recurring | Level 2 | U.S. large-cap
Price risk management assets:
NDT funds		165	159
Recurring | Level 2 | U.S. mid/small-cap
Price risk management assets:
NDT funds		52	50
Recurring | Level 2 | U.S. government sponsored agency
Price risk management assets:
NDT funds		4	6
Recurring | Level 2 | Municipality
Price risk management assets:
NDT funds		88	83
Recurring | Level 2 | Investment-grade corporate
Price risk management assets:
NDT funds		45	47
Recurring | Level 2 | Other
Price risk management assets:
NDT funds		1	3
Recurring | Level 2 | Receivables/payables, net
Price risk management assets:
NDT funds		3	2
Recurring | Level 3
Price risk management assets:
Gross		34	96
Total assets		40	102
Price risk management liabilities:
Gross		22	42
Recurring | Level 3 | Auction Rate Securities
Price risk management assets:
Auction rate securities	[2]	6	6
Energy Commodities, net | Recurring
Price risk management assets:
Gross		582	693
Price risk management liabilities:
Gross		520	539
Energy Commodities, net | Recurring | Level 1
Price risk management assets:
Gross		0	0
Price risk management liabilities:
Gross		0	0
Energy Commodities, net | Recurring | Level 2
Price risk management assets:
Gross		548	597
Price risk management liabilities:
Gross		498	497
Energy Commodities, net | Recurring | Level 3
Price risk management assets:
Gross		34	96
Price risk management liabilities:
Gross		$ 22	$ 42
[1]	Current portion is included in "Restricted cash and cash equivalents" and long-term portion, when applicable, is included in "Other noncurrent assets" on the Balance Sheets.
[2]	Included in "Other investments" on the Balance Sheets.

Fair Value Measurements and C59

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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reconciliation of Total
Balance at beginning of period	$ 74	$ 137	$ 60	$ 119
Total realized/unrealized gains (losses) included in earnings	(38)	(124)	22	(141)
Purchases		(39)		(39)
Sales		64		64
Settlements	(22)	(27)	(67)	3
Transfers into Level 3		6	1	10
Transfers out of Level 3	4		2	1
Balance at end of period	18	17	18	17
Auction Rate Securities
Reconciliation of Auction Rate Securities
Balance at beginning of period	6	8	6	8
Sales		(1)		(1)
Balance at end of period	6	7	6	7
Energy Commodities, net
Reconciliation of Energy Commodities, net
Balance at beginning of period	68	129	54	111
Total realized/unrealized gains (losses) included in earnings	(38)	(124)	22	(141)
Purchases		(39)		(39)
Sales		65		65
Settlements	(22)	(27)	(67)	3
Transfers into Level 3		6	1	10
Transfers out of Level 3	4		2	1
Balance at end of period	$ 12	$ 10	$ 12	$ 10

Fair Value Measurements and C60

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		Jun. 30, 2016	Dec. 31, 2015
Auction Rate Securities
Fair Value Inputs [Abstract]
Asset, fair value net	[1]	$ 6	$ 6
Auction Rate Securities | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	[2]	40.00%	46.00%
Auction Rate Securities | Discounted Cash Flow | Maximum
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	[2]	40.00%	47.00%
Auction Rate Securities | Discounted Cash Flow | Weighted Average
Fair Value Inputs [Abstract]
Modeled from SIFMA Index	[2]	40.00%	46.50%
Natural gas contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, fair value, net	[3]	$ 19	$ 55
Natural gas contracts | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	10.00%	10.00%
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]	67.00%	50.00%
Power sales contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, fair value, net	[4]	$ (6)	$ 13
Power sales contracts | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%	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]	100.00%	100.00%
FTR purchase contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, fair value, net	[5]	$ 1	$ (2)
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]		$ (10)
Heat rate call options | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]		100.00%
Heat rate call options | Discounted Cash Flow | Maximum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]		100.00%
Heat rate call options | Discounted Cash Flow | Weighted Average
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]		100.00%
CRR purchase contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, fair value, net	[5]	$ (2)	$ (2)
CRR purchase contracts | Discounted Cash Flow | Minimum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%	100.00%
CRR purchase contracts | Discounted Cash Flow | Maximum
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%	100.00%
CRR purchase contracts | Discounted Cash Flow | Weighted Average
Fair Value Inputs [Abstract]
Proprietary model used to calculate forward prices	[2]	100.00%	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.

Fair Value Measurements and C61

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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	$ (38)	$ (124)	$ 22	$ (141)
Recurring | Energy Commodities, Net | Wholesale energy
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(10)	(131)	31	(110)
Change in unrealized gains (losses) relating to positions still held at the reporting date	(9)	(36)	(4)	(42)
Recurring | Energy Commodities, Net | Retail Energy
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(27)	8	(9)	(32)
Change in unrealized gains (losses) relating to positions still held at the reporting date	(20)	7	(16)	0
Recurring | Energy Commodities, Net | Fuel and energy purchases
Net gains and losses on assets and liabilities [Abstract]
Total gains (losses) included in earnings	(1)	(1)	0	1
Change in unrealized gains (losses) relating to positions still held at the reporting date	$ 1	$ (4)	$ 0	$ (4)

Fair Value Measurements and C62

Fair Value Measurements and Credit Concentration (Nonrecurring Fair Value Measurements) (Details) - Fair Value, Measurements, Nonrecurring $ in Millions	6 Months Ended
	Jun. 30, 2016USD ($)
Bell Bend COLA (June 30, 2016)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pre-tax Loss	$ 204	[1]
Bell Bend COLA (June 30, 2016) | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring measurement asset value	0
Assets, Fair Value Disclosure	0
Bell Bend COLA (June 30, 2016) | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring measurement asset value	204	[2]
Harquahala plant (June 30, 2016)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pre-tax Loss	9	[1]
Harquahala plant (June 30, 2016) | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring measurement asset value	0
Assets, Fair Value Disclosure	0
Harquahala plant (June 30, 2016) | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring measurement asset value	$ 9	[2]
Minimum | Bell Bend COLA (June 30, 2016) | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation technique model	100.00%	[3]
Minimum | Harquahala plant (June 30, 2016) | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation technique model	100.00%	[3]
Maximum | Bell Bend COLA (June 30, 2016) | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation technique model	100.00%	[3]
Maximum | Harquahala plant (June 30, 2016) | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation technique model	100.00%	[3]
Weighted Average | Bell Bend COLA (June 30, 2016) | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation technique model	100.00%	[3]
Weighted Average | Harquahala plant (June 30, 2016) | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation technique model	100.00%	[3]
[1]	The losses are included in "Impairments" on the Statement of Income.
[2]	Represents carrying value before fair value measurement.
[3]	The range and weighted average represent the percentage of fair value derived from the unobservable inputs.

Fair Value Measurements and C63

Fair Value Measurements and Credit Concentration (Financial Instruments Not Recorded at Fair Value and Credit Concentration) (Details) $ in Millions	Jun. 30, 2016USD ($)counterparty	Dec. 31, 2015USD ($)
Credit Concentration Associated with Financial Instruments (Numeric) [Abstract]
Gross credit exposure from energy trading partners	$ 425
Net credit exposure to energy trading partners	265
Dollar exposure to top ten energy trading counterparties	$ 124
Percentage exposure to top ten energy trading counterparties	47.00%
Number of counterparties in top ten that have investment grade credit rating | counterparty	8
Percentage of top ten's exposure that consists of counterparties with investment grade credit rating	88.00%
Carrying Amount
Fair Value of Financial Instruments Not Recorded at Fair Value - Other
Long-term debt	$ 3,901	$ 4,186
Fair Value
Fair Value of Financial Instruments Not Recorded at Fair Value - Other
Long-term debt	$ 3,458	$ 3,343

Derivative Instruments and He64

Derivative Instruments and Hedging Activities (Intro) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
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	$ 16		$ 16
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)	(194)	$ 20	$ (134)	$ 39
Retail Energy
Pre-tax Gains (Losses) of Economic Activity (Details) [Abstract]
Pre-tax gain (loss)	(36)	(9)	(35)	(22)
Fuel and energy purchases
Pre-tax Gains (Losses) of Economic Activity (Details) [Abstract]
Pre-tax gain (loss)	$ 84	$ 26	$ 101	$ 60

Derivative Instruments and He65

Derivative Instruments and Hedging Activities (Commodity Volumes) (Details)	Jun. 30, 2016MMBTUMW-MMWhTbbl	[2]
Power | Sales | 2016
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	(21,987,241)	[1]
Power | Sales | 2017
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	(24,721,341)
Power | Sales | 2018
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	(7,568,633)
Power | Sales | Thereafter
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	(719,594)
Capacity | Sales | 2016
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MW-M	(3,050)	[1]
Capacity | Sales | 2017
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MW-M	(3,750)
Capacity | Sales | 2018
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MW-M	(3,746)
Capacity | Sales | Thereafter
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MW-M	(1,559)
Gas | Purchases | 2016
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MMBTU	(87,035,186)	[1]
Gas | Purchases | 2017
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MMBTU	(29,084,926)
Gas | Purchases | 2018
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MMBTU	(16,333,048)
Gas | Purchases | Thereafter
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MMBTU	(3,206,105)
FTRs | Purchases | 2016
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MW-M	(7,212)	[1]
FTRs | Purchases | 2017
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MW-M	(2,929)
FTRs | Purchases | 2018
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MW-M	0
FTRs | Purchases | Thereafter
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MW-M	0
Oil | Purchases | 2016
Derivative [Line Items]
Volumes (in barrels) | bbl	33,655	[1]
Oil | Purchases | 2017
Derivative [Line Items]
Volumes (in barrels) | bbl	0
Oil | Purchases | 2018
Derivative [Line Items]
Volumes (in barrels) | bbl	0
Oil | Purchases | Thereafter
Derivative [Line Items]
Volumes (in barrels) | bbl	0
CRR purchase contracts | Purchases | 2016
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	(1,138,739)	[1]
CRR purchase contracts | Purchases | 2017
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	(641,989)
CRR purchase contracts | Purchases | 2018
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	0
CRR purchase contracts | Purchases | Thereafter
Derivative [Line Items]
Volumes (in MWh, MW-Month, MMBtu) | MWh	0
Emission Allowances | Purchases | 2016
Derivative [Line Items]
Volumes (tons) | T	(3,322,531)	[1]
Emission Allowances | Purchases | 2017
Derivative [Line Items]
Volumes (tons) | T	(97,548)
Emission Allowances | Purchases | 2018
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 He66

Derivative Instruments and Hedging Activities (Fair Values) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Fair Values by Balance Sheet Location [Abstract]
Asset value	$ 582	$ 693
Liability value	520	539
Not Designated as Hedging Instrument
Fair Values by Balance Sheet Location [Abstract]
Asset value	582	693
Liability value	520	539
Not Designated as Hedging Instrument | Current Assets | Energy Commodities, net
Fair Values by Balance Sheet Location [Abstract]
Asset value	429	562
Not Designated as Hedging Instrument | Noncurrent Assets | Energy Commodities, net
Fair Values by Balance Sheet Location [Abstract]
Asset value	153	131
Not Designated as Hedging Instrument | Current Liabilities | Energy Commodities, net
Fair Values by Balance Sheet Location [Abstract]
Liability value	393	431
Not Designated as Hedging Instrument | Noncurrent Liabilities | Energy Commodities, net
Fair Values by Balance Sheet Location [Abstract]
Liability value	$ 127	$ 108

Derivative Instruments and He67

Derivative Instruments and Hedging Activities (Gains and Losses) (Details) - Energy Commodities, net - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	$ 7	$ 10	$ 12	$ 17
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)	(1)	2	(4)	0
Cash Flow Hedges | Fuel and energy purchases
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	7	8	15	16
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)	1	0	1	1
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivative, net	(64)	90	141	15
Not Designated as Hedging Instrument | Wholesale energy
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivative, net	(75)	138	172	54
Not Designated as Hedging Instrument | Retail Energy
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivative, net	(22)	8	(3)	(31)
Not Designated as Hedging Instrument | Fuel and energy purchases
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivative, net	$ 33	$ (56)	$ (28)	$ (8)

Derivative Instruments and He68

Derivative Instruments and Hedging Activities (Offsetting Derivative Instruments and Credit Risk-Related Features) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Assets
Gross	$ 582	$ 693
Eligible for Offset, Derivative Instruments	428	437
Eligible for Offset, Cash Collateral Received	16	74
Net	138	182
Liabilities
Gross	520	539
Eligible for Offset, Derivative Instruments	428	437
Eligible for Offset, Cash Collateral Pledged	9	30
Net	83	$ 72
Derivative, Credit Risk Related Contingent Features [Abstract]
Aggregate fair value of derivative instruments in a net liability position	81
Aggregate fair value of collateral posted on these derivative instruments	89
Aggregate fair value of additional collateral requirements, primarily related to further adequate assurance features	$ 7

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at Beginning of Period	$ 501
Accretion expense	19
Changes in estimate of cash flow or settlement date	(4)
Obligations settled	(5)
Balance at End of Period	$ 511

NDT Funds (Details)

NDT Funds (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Amortized cost - maturity less than 1 year		$ 8		$ 8
Amortized cost - maturity between 1 and 5 years		103		103
Amortized cost - maturity between 6 and 10 years		73		73
Amortized cost - maturity in excess of 10 years		51		51
Amortized cost total		235		235
Fair value - maturity less than 1 year		8		8
Fair value - maturity between 1 and 5 years		106		106
Fair value - maturity between 6 and 10 years		77		77
Fair value - maturity in excess of 10 years		59		59
Fair value total		250		250
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Proceeds from sales of NDT securities		38	$ 62	92	$ 100
Gross realized gains	[1]	11	8	17	13
Gross realized losses	[1]	5	$ 6	13	$ 9
NDT Funds
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		552		552		$ 538
Gross unrealized gains		432		432		413
Gross unrealized losses		0		0		0
Fair value		984		984		951
NDT Funds | Cash and cash equivalents
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		4		4		11
Gross unrealized gains		0		0		0
Gross unrealized losses		0		0		0
Fair value		4		4		11
NDT Funds | Equity securities
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		310		310		297
Gross unrealized gains		417		417		406
Gross unrealized losses		0		0		0
Fair value		727		727		703
NDT Funds | Debt securities
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		235		235		230
Gross unrealized gains		15		15		7
Gross unrealized losses		0		0		0
Fair value		250		250		237
NDT Funds | Receivables/payables, net
Available-for-sale Securities, Balance Sheet, Reported Amounts [Abstract]
Amortized cost		3		3		0
Gross unrealized gains		0		0		0
Gross unrealized losses		0		0		0
Fair value		$ 3		$ 3		$ 0
[1]	Excludes the impact of other-than-temporary impairment charges recognized on the Statements of Income.

Accumulated Other Comprehensi71

Accumulated Other Comprehensive Income (Loss) (After-tax Changes by Component) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			$ (26)	$ (23)
Amounts arising during the period			11	44
Reclassifications from accumulated other comprehensive income			(2)	(4)
Total other comprehensive income (loss)	$ 5	$ 36	9	40
Balance at end of period	(17)	17	(17)	17
Available- for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			194	202
Amounts arising during the period			11	1
Reclassifications from accumulated other comprehensive income			(2)	(2)
Total other comprehensive income (loss)			9	(1)
Balance at end of period	203	201	203	201
Qualifying derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			44	63
Amounts arising during the period			0	0
Reclassifications from accumulated other comprehensive income			(7)	(10)
Total other comprehensive income (loss)			(7)	(10)
Balance at end of period	37	53	37	53
Prior service costs
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			3	7
Amounts arising during the period			0	(3)
Reclassifications from accumulated other comprehensive income			0	(1)
Total other comprehensive income (loss)			0	(4)
Balance at end of period	3	3	3	3
Actuarial gain (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			(267)	(295)
Amounts arising during the period			0	46
Reclassifications from accumulated other comprehensive income			7	9
Total other comprehensive income (loss)			7	55
Balance at end of period	$ (260)	$ (240)	$ (260)	$ (240)

Accumulated Other Comprehensi72

Accumulated Other Comprehensive Income (Loss) (Income (Expense) Effect of Reclassifications) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Affected Line Item on the Statements of Income [Line Items]
Wholesale energy	$ 389	$ 561	$ 1,189	$ 1,237
Fuel and energy purchases	(347)	(382)	(838)	(897)
Other Income (Expense) - net	6	3	12	10
Total Pre-tax	(6)	(17)	251	132
Income Taxes	3	43	(103)	(10)
Reclassification out of AOCI
Affected Line Item on the Statements of Income [Line Items]
Income (Loss) from Continuing Operations After Income Taxes	3	3	2	4
Reclassification out of AOCI | Available-for-sale securities
Affected Line Item on the Statements of Income [Line Items]
Other Income (Expense) - net	6	2	4	4
Income Taxes	(3)	(1)	(2)	(2)
Income (Loss) from Continuing Operations After Income Taxes	3	1	2	2
Reclassification out of AOCI | Qualifying derivatives
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	7	10	12	17
Income Taxes	(3)	(4)	(5)	(7)
Income (Loss) from Continuing Operations After Income Taxes	4	6	7	10
Reclassification out of AOCI | Qualifying derivatives | Commodity contracts
Affected Line Item on the Statements of Income [Line Items]
Wholesale energy	(1)	2	(4)	0
Fuel and energy purchases	7	8	15	16
Other Income (Expense) - net	1	0	1	1
Reclassification out of AOCI | Defined benefit plans
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	(6)	(7)	(11)	(14)
Income Taxes	2	3	4	6
Income (Loss) from Continuing Operations After Income Taxes	(4)	(4)	(7)	(8)
Reclassification out of AOCI | Defined benefit plans | Prior service costs
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	0	1	0	1
Reclassification out of AOCI | Defined benefit plans | Net actuarial loss
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	$ (6)	$ (8)	$ (11)	$ (15)

Uncategorized Items - tln-20160

Label	Element	Value
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	$ 90,000,000
Retained Earnings [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	90,000,000
Predecessor Member's Equity [Member]
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	$ 32,000,000	[1]
[1]	Represents Talen Energy Supply's predecessor member's equity balance and activity prior to the June 1, 2015 spinoff transaction.