Employee benefit plans

9 Months Ended

Sep. 30, 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 credit for the Company's pension and other postretirement benefit plans were as follows:

	Pension Benefits				Other Postretirement Benefits
Three Months Ended September 30,	2021		2020		2021		2020
	(In thousands)
Components of net periodic benefit credit:
Service cost	$	—	$	—	$	400	$	383
Interest cost	2,455		3,023		466		609
Expected return on assets	(4,894)		(4,987)		(1,275)		(1,115)
Amortization of prior service credit	—		—		(349)		(349)
Amortization of net actuarial loss	2,004		1,793		6		71
Net periodic benefit credit, including amount capitalized	(435)		(171)		(752)		(401)
Less amount capitalized	—		—		46		39
Net periodic benefit credit	$	(435)	$	(171)	$	(798)	$	(440)

	Pension Benefits				Other Postretirement Benefits
Nine Months Ended September 30,	2021		2020		2021		2020
	(In thousands)
Components of net periodic benefit credit:
Service cost	$	—	$	—	$	1,200	$	1,149
Interest cost	7,365		9,070		1,398		1,827
Expected return on assets	(14,682)		(14,962)		(3,825)		(3,764)
Amortization of prior service credit	—		—		(1,047)		(1,048)
Amortization of net actuarial loss	6,012		5,379		18		215
Net periodic benefit credit, including amount capitalized	(1,305)		(513)		(2,256)		(1,621)
Less amount capitalized	—		—		129		106
Net periodic benefit credit	$	(1,305)	$	(513)	$	(2,385)	$	(1,727)

The components of net periodic benefit 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 $2.3 million for the three and nine months ended September 30, 2021, respectively. The Company's net periodic benefit cost for these plans for the three and nine months ended September 30, 2020, was $1.0 million and $2.9 million, respectively. The components of net periodic benefit cost for these plans are included in other income on the Consolidated Statements of Income.