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