Overview and Summary of Significant Accounting Policies Overview and Summary of Significant Accounting Polices (Tables)

12 Months Ended

Dec. 31, 2016

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Expected Service and Interest Costs

The 2016 service costs and interest costs included in Note 10 – Benefit Plans reflect the change in methodology described above. The impact of the change in approach on service costs and interest costs in 2016 is shown below:

$ in millions	2016 Service Cost							2016 Interest Cost
	Disaggregated rate approach		Aggregate rate approach		Impact of change			Disaggregated rate approach		Aggregate rate approach		Impact of change
Total Pension	$	5.7	$	6.1	$	(0.4	)	$	14.7	$	17.9	$	(3.2	)
Total Postretirement Benefits	0.2		0.2		—			0.6		0.7		(0.1		)
Total	$	5.9	$	6.3	$	(0.4	)	$	15.3	$	18.6	$	(3.3	)

THE DAYTON POWER AND LIGHT COMPANY [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Expected Service and Interest Costs

The 2016 service costs and interest costs included in Note 9 – Benefit Plans reflect the change in methodology described above. The impact of the change in approach on service costs and interest costs in 2016 is shown below:

$ in millions	2016 Service Cost							2016 Interest Cost
	Disaggregated rate approach		Aggregate rate approach		Impact of change			Disaggregated rate approach		Aggregate rate approach		Impact of change
Total Pension	$	5.7	$	6.1	$	(0.4	)	$	14.7	$	17.9	$	(3.2	)
Total Postretirement Benefits	0.2		0.2		—			0.6		0.7		(0.1		)
Total	$	5.9	$	6.3	$	(0.4	)	$	15.3	$	18.6	$	(3.3	)