Property, Plant and Equipment (Tables)

3 Months Ended

Mar. 31, 2017

Property, Plant and Equipment [Line Items]

Schedule of Jointly Owned Utility Plants [Table Text Block]

DP&L’s undivided ownership interest in such facilities at March 31, 2017, is as follows:

	DP&L 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	$	—	$	—	$	—
Killen - Unit 2	67.0	402	7.0		1.0		1.0
Miami Fort - Units 7 and 8	36.0	368	28.0		1.0		5.0
Stuart - Units 1 through 4	35.0	808	1.0		1.0		—
Zimmer - Unit 1	28.1	371	12.0		1.0		5.0
Transmission (at varying percentages)			43.0		11.0		—
Total		2,078	$	91.0	$	15.0	$	11.0

Schedule of Change in Asset Retirement Obligation [Table Text Block]

Changes in the Liability for Generation AROs

$ in millions
Balance January 1, 2017	$	138.8
Revisions to cash flow and timing estimates	(4.4		)
Accretion expense	1.1
Settlements	0.1
Balance March 31, 2017	$	135.6

Subsidiaries [Member]

Property, Plant and Equipment [Line Items]

Schedule of Jointly Owned Utility Plants [Table Text Block]

DP&L’s undivided ownership interest in such facilities at March 31, 2017, is as follows:

	DP&L Share		DP&L 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	$	—	$	—	$	—
Killen - Unit 2	67.0	402	7.0		1.0		1.0
Miami Fort - Units 7 and 8	36.0	368	28.0		1.0		5.0
Stuart - Units 1 through 4	35.0	808	1.0		1.0		—
Zimmer - Unit 1	28.1	371	12.0		1.0		5.0
Transmission (at varying percentages)			99.0		67.0		—
Total		2,078	$	147.0	$	71.0	$	11.0

Schedule of Change in Asset Retirement Obligation [Table Text Block]

Changes in the Liability for Generation AROs

$ in millions
Balance January 1, 2017	$	135.2
Revisions to cash flow and timing estimates	(4.4		)
Accretion expense	1.4
Settlements	0.1
Balance March 31, 2017	$	132.3