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, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Income (loss) from continuing operations, after Adjustment to Retained Earnings, Basic Earnings									$ 3
Income from continuing operations, net of tax									$ 8	$ 331	$ 705
Weighted Average Number of Shares Outstanding, Basic (in shares)									660	687	720
Income (Loss) from Continuing Operations, Per Basic Share	$ (0.30)	$ 0.26	$ (0.16)	$ 0.20	$ (0.11)	$ 0.26	$ 0.11	$ 0.21	$ 0.00	$ 0.48	$ 0.98
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants (in shares)									0	0	1
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements (in shares)									2	2	3
Income (Loss) From Continuing Operations Diluted										$ 331	$ 705
Weighted Average Number of Shares Outstanding, Diluted (in shares)									662	689	724
Income (Loss) from Continuing Operations, Per Diluted Share	$ (0.30)	$ 0.26	$ (0.16)	$ 0.20	$ (0.11)	$ 0.26	$ 0.11	$ 0.21	$ 0.00	$ 0.48	$ 0.97
Income (loss) from continuing operations, after Adjustment to Retained Earnings, Diluted Earnings									$ 3
Temporary Equity, Accretion to Redemption Value									$ 4	$ 0
Employee Stock Option [Member]
Class of Stock [Line Items]
Income (Loss) from Continuing Operations, Per Diluted Share									$ 0.00	$ 0.00	0.00
Restricted Stock Units (RSUs) [Member]
Class of Stock [Line Items]
Income (Loss) from Continuing Operations, Per Diluted Share									$ 0.00	$ 0.00	$ (0.01)
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
Equity Option [Member]
Class of Stock [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units									0	$ 0	$ 0
DPL Subsidiary [Member]
Class of Stock [Line Items]
Temporary Equity, Accretion to Redemption Value									$ 5