Summary of Significant Accounting Policies (Recently Issued Accounting Standards) (Details) $ in Millions	9 Months Ended
Sep. 30, 2015 USD ($)
Significant Accounting Policies [Line Items]
Deferred financing costs to be reclassed and deducted from debt amount	$ 17.6
THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Deferred financing costs to be reclassed and deducted from debt amount	$ 4.6

This is the amount of Deferred Financing costs that will be reclassed from other non-current assets to reduce the amount of debt liabilities. This is as a result of ASU 2015-03 issued by FASB in April 2015. The standard is effective for annual reporting beginning December, 15, 2015

No definition available.

Name:	dpl_DeferredFinancingCostsThatWillBeReclassedAndDeductedFromDebtAmount
Namespace Prefix:	dpl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration