Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2019

Entity Information [Line Items]

Schedule of Net Periodic Benefit Cost / (Income)

The net periodic benefit cost of the pension benefit plans for the three and six months ended June 30, 2019 and 2018 was:

	Three months ended						Six months ended
	June 30,						June 30,
$ in millions	2019			2018			2019			2018
Service cost	$	0.9		$	1.5		$	1.8		$	3.0
Interest cost	3.8			3.5			7.5			6.9
Expected return on plan assets	(5.0		)	(5.4		)	(10.0		)	(10.6		)
Amortization of unrecognized:
Prior service cost	0.3			0.3			0.6			0.5
Actuarial loss	1.0			1.6			2.1			3.2
Net periodic benefit cost	$	1.0		$	1.5		$	2.0		$	3.0

THE DAYTON POWER AND LIGHT COMPANY [Member]

Entity Information [Line Items]

Schedule of Net Periodic Benefit Cost / (Income)

The net periodic benefit cost of the pension benefit plans for the three and six months ended June 30, 2019 and 2018 was:

	Three months ended						Six months ended
	June 30,						June 30,
$ in millions	2019			2018			2019			2018
Service cost	$	0.9		$	1.5		$	1.8		$	3.0
Interest cost	3.8			3.5			7.5			6.9
Expected return on plan assets	(5.0		)	(5.4		)	(10.0		)	(10.6		)
Amortization of unrecognized:
Prior service cost	0.4			0.3			0.9			0.7
Actuarial loss	1.8			2.4			3.5			4.7
Net periodic benefit cost	$	1.9		$	2.3		$	3.7		$	4.7