Schedule II Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Provision for Uncollectible Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 898	$ 909	$ 923
Additions	3,766	4,011	4,924
Deductions	3,829	4,022	4,938
Balance at End of Period	835	898	909
Provision for Uncollectible Accounts [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	897	909	923
Additions	3,766	4,011	4,924
Deductions	3,828	4,023	4,938
Balance at End of Period	835	897	909
Valuation Allowance For Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	18,900	13,721	12,349
Additions	1,626	5,179	2,159
Deductions	3,280	0	787
Balance at End of Period	17,246	18,900	13,721
Assets held for sale, current [Member] | Provision for Uncollectible Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	369	251	161
Additions	2,035	3,633	1,232
Deductions	2,291	3,515	1,142
Balance at End of Period	$ 113	$ 369	$ 251