Earnings Per Share (Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent										$ 985	$ (507)	$ (20)
Income (loss) from continuing operations, after Adjustment to Retained Earnings, Basic Earnings	[1]											$ (25)
Weighted Average Number of Shares Outstanding, Basic (in shares)										662	660	660
Income (Loss) from Continuing Operations, Per Basic Share		$ 0.15	$ 0.15	$ 0.15	$ 1.04	$ (1.03)	$ 0.22	$ 0.08	$ (0.04)	$ 1.49	$ (0.77)	$ (0.04)
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements (in shares)										3	0	0
Weighted Average Number of Shares Outstanding, Diluted (in shares)										665	660	660
Income (Loss) from Continuing Operations, Per Diluted Share		$ 0.15	$ 0.15	$ 0.15	$ 1.03	$ (1.03)	$ 0.22	$ 0.08	$ (0.04)	$ 1.48	$ (0.77)	$ (0.04)
Income (loss) from continuing operations, after Adjustment to Retained Earnings, Diluted Earnings	[1]											$ (25)
Temporary Equity, Accretion to Redemption Value										$ 4	$ 25
Restricted Stock Units (RSUs) [Member]
Class of Stock [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units										$ 0	$ 0	$ 0
Dilutive Securities Effect On Basic EPS, dilutive Restricted Stock Units, per diluted share										$ (0.01)	$ 0	$ 0
DPL Subsidiary [Member]
Class of Stock [Line Items]
Temporary Equity, Accretion to Redemption Value												$ 5

[1] Loss from continuing operations, net of tax, of $20 million less the $5 million adjustment to retained earnings to record the DP&L redeemable preferred stock at its redemption value as of December 31, 2016.