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