Employee benefit plans

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Employee benefit plans

Employee benefit plans

Pension and other postretirement plans

The Company has noncontributory qualified defined benefit pension plans and other postretirement benefit plans for certain eligible employees. Components of net periodic benefit cost (credit) for the Company's pension and other postretirement benefit plans were as follows:

	Pension Benefits				Other Postretirement Benefits
Three Months Ended March 31,	2021		2020		2021		2020
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	—	$	—	$	400	$	352
Interest cost	2,455		2,973		466		591
Expected return on assets	(4,894)		(4,761)		(1,275)		(1,248)
Amortization of prior service credit	—		—		(349)		(297)
Amortization of net actuarial loss	2,004		1,863		6		2
Net periodic benefit cost (credit), including amount capitalized	(435)		75		(752)		(600)
Less amount capitalized	—		—		39		32
Net periodic benefit cost (credit)	$	(435)	$	75	$	(791)	$	(632)

The components of net periodic benefit cost (credit), other than the service cost component, are included in other income on the Consolidated Statements of Income. The service cost component is included in operation and maintenance expense on the Consolidated Statements of Income.

Nonqualified defined benefit plans

In addition to the qualified defined benefit pension plans reflected in the table at the beginning of this note, the Company also has unfunded, nonqualified defined benefit plans for executive officers and certain key management employees. The Company's net periodic benefit cost for these plans was $769,000 and $1.0 million for the three months ended March 31, 2021 and 2020, respectively. The components of net periodic benefit cost for these plans are included in other income on the Consolidated Statements of Income.