Earnings (Loss) Per Share for Talen Energy Corporation (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
	Jun. 01, 2015	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Income (Numerator)
Income (Loss) from Continuing Operations After Income Taxes										$ (341)		$ 187	$ (262)
Income (Loss) from Discontinued Operations (net of income taxes)										0		223	32
Net Income (Loss) Attributable to Member		$ (62)	$ (401)	$ 26	$ 96	$ 362	$ 101	$ 13	$ (66)	$ (341)		$ 410	$ (230)
Shares of Common Stock (Denominator)
Weighted-average shares - Basic EPS (in shares)										109,898,000		83,524,000	83,524,000
Weighted-average shares - Diluted EPS (in shares)										109,898,000		83,524,000	83,524,000
Antidilutive securities excluded from computation of earnings per share (in shares)										731,000
Common Stock
Schedule of Capitalization, Equity [Line Items]
Stock issuance (shares)	128,499,023
Consummation of spinoff transaction, shares	83,524,365									83,524,000	[1],[2]
Common stock issued for acquisition of RJS Power, shares	44,974,658									44,975,000	[1]

[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 for additional information on the spinoff.