Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Line Items]

Summary of Property, Plant, and Equipment

The following is a summary of DPL’s Property, plant and equipment with corresponding composite depreciation rates at December 31, 2017 and 2016:

	December 31, 2017			December 31, 2016
$ in millions			Composite Rate			Composite Rate
Regulated:
Transmission	$	242.7	4.0%	$	247.3	3.9%
Distribution	1,197.5		4.9%	1,141.1		4.7%
General	13.7		7.1%	13.7		7.4%
Non-depreciable	64.7		N/A	63.5		N/A
Total regulated	1,518.6			1,465.6
Unregulated:
Production / Generation	10.9		63.2%	483.2		11.7%
Other	19.4		7.0%	17.0		8.0%
Non-depreciable	5.8		N/A	19.8		N/A
Total unregulated	36.1			520.0
Total property, plant and equipment in service	$	1,554.7	5.0%	$	1,985.6	6.1%

Ownership Interests

DPL’s undivided ownership interest in such facilities at December 31, 2017, is as follows:

	DPL Share		DPL Carrying Value
	Ownership (%)	Summer Production Capacity (MW)	Gross Plant In Service ($ in millions)		Accumulated Depreciation ($ in millions)		Construction Work in Process ($ in millions)
Jointly-owned production units
Conesville - Unit 4	16.5	129	$	0.7	$	0.7	$	1.9
Killen - Unit 2	67.0	402	9.6		8.2		—
Stuart - Units 2 through 4	35.0	606	1.8		1.8		—
Transmission (at varying percentages)			45.6		13.3		—
Total		1,137	$	57.7	$	24.0	$	1.9

Changes in the Liability for Generation AROs

Changes in the Liability for Generation AROs

$ in millions
Balance at December 31, 2015	$	65.9
Calendar 2016
Additions	70.2
Accretion expense	2.7
Settlements	—
Balance at December 31, 2016	138.8
Calendar 2017
Additions	0.1
Revisions to cash flow and timing estimates	(6.3		)
Accretion expense	3.7
Settlements	(0.1		)
Reductions due to plants sold or held-for-sale	(5.0		)
Balance at December 31, 2017	$	131.2

Changes in the Liability for Transmission and Distribution Asset Removal Costs

Changes in the Liability for Transmission and Distribution Asset Removal Costs

$ in millions
Balance at December 31, 2015	$	121.8
Calendar 2016
Additions	11.7
Settlements	(7.0		)
Balance at December 31, 2016	126.5
Calendar 2017
Additions	12.0
Settlements	(5.7		)
Balance at December 31, 2017	$	132.8

THE DAYTON POWER AND LIGHT COMPANY [Member]

Property, Plant and Equipment [Line Items]

Summary of Property, Plant, and Equipment

The following is a summary of DP&L’s Property, plant and equipment with corresponding composite depreciation rates at December 31, 2017 and 2016:

	December 31, 2017			December 31, 2016
$ in millions			Composite Rate			Composite Rate
Regulated:
Transmission	$	414.6	2.4%	$	421.1	2.3%
Distribution	1,735.9		3.4%	1,693.5		3.2%
General	31.2		3.1%	31.6		3.2%
Non-depreciable	64.6		N/A	63.5		N/A
Total regulated	2,246.3			2,209.7
Unregulated:
Other	0.2		2.7%	0.3		2.7%
Non-depreciable	0.7		N/A	3.5		N/A
Total unregulated	0.9			3.8
Total property, plant and equipment in service	$	2,247.2	3.4%	$	2,213.5	4.6%

Changes in the Liability for Generation AROs

Changes in the Liability for Generation AROs

$ in millions
Balance at December 31, 2015	$	5.0
Calendar 2016
Additions	2.7
Accretion expense	0.3
Settlements	0.2
Balance at December 31, 2016	8.2
Calendar 2017
Accretion expense	0.1
Settlements	(0.3		)
Balance at December 31, 2017	$	8.0

Changes in the Liability for Transmission and Distribution Asset Removal Costs

Changes in the Liability for Transmission and Distribution Asset Removal Costs

$ in millions
Balance at December 31, 2015	$	121.8
Calendar 2016
Additions	11.7
Settlements	(7.0		)
Balance at December 31, 2016	126.5
Calendar 2017
Additions	12.0
Settlements	(5.7		)
Balance at December 31, 2017	$	132.8