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