Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2018

The net periodic benefit cost of the pension benefit plans for the three months ended March 31, 2018 and 2017 was:



	Three months ended
	March 31,
$ in millions	2018			2017
Service cost	$	1.5		$	1.4
Interest cost	3.4			3.6
Expected return on plan assets	(5.2		)	(5.7		)
Plan curtailment ^(a)	—			4.1
Amortization of unrecognized:
Prior service cost	0.2			0.4
Actuarial loss	1.6			1.3
Net periodic benefit cost	$	1.5		$	5.1


(a)	As a result of the decision to retire certain of DP&L's coal-fired plants, we recognized a plan curtailment of $4.1 million in the first quarter of 2017. See Note 15 – Fixed-asset Impairments for more information.

Benefit payments, which reflect future service, are estimated to be paid as follows:



$ in millions
Estimated balance to be paid during	Pension
2018	$	21.3
2019	$	28.2
2020	$	27.9
2021	$	27.6
2022	$	27.3
2023 - 2027	$	131.3

The net periodic benefit cost of the pension benefit plans for the three months ended March 31, 2018 and 2017 was:



	Three months ended
	March 31,
$ in millions	2018			2017
Service cost	$	1.5		$	1.4
Interest cost	3.4			3.6
Expected return on plan assets	(5.2		)	(5.7		)
Plan curtailment ^(a)	—			5.6
Amortization of unrecognized:
Prior service cost	0.4			0.5
Actuarial loss	2.3			2.2
Net periodic benefit cost	$	2.4		$	7.6


(a)	As a result of the decision to retire certain of DP&L's coal-fired plants, we recognized a plan curtailment of $5.6 million in the first quarter of 2017.

Benefit payments, which reflect future service, are estimated to be paid as follows:



$ in millions
Estimated balance to be paid during	Pension
2018	$	21.3
2019	$	28.2
2020	$	27.9
2021	$	27.6
2022	$	27.3
2023 - 2027	$	131.3