Employee benefit plans

6 Months Ended

Jun. 30, 2020

Retirement Benefits [Abstract]

Pension and other postretirement 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 June 30,	2020		2019		2020		2019
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	—	$	—	$	414	$	227
Interest cost	3,074		3,840		627		713
Expected return on assets	(5,214)		(3,998)		(1,401)		(1,182)
Amortization of prior service credit	—		—		(402)		(228)
Amortization of net actuarial (gain) loss	1,723		1,418		142		(42)
Net periodic benefit cost (credit), including amount capitalized	(417)		1,260		(620)		(512)
Less amount capitalized	—		—		35		27
Net periodic benefit cost (credit)	$	(417)	$	1,260	$	(655)	$	(539)

	Pension Benefits				Other Postretirement Benefits
Six Months Ended June 30,	2020		2019		2020		2019
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	—	$	—	$	766	$	571
Interest cost	6,047		7,613		1,218		1,493
Expected return on assets	(9,975)		(9,118)		(2,649)		(2,402)
Amortization of prior service credit	—		—		(699)		(577)
Amortization of net actuarial loss	3,586		2,773		144		55
Net periodic benefit cost (credit), including amount capitalized	(342)		1,268		(1,220)		(860)
Less amount capitalized	—		—		67		58
Net periodic benefit cost (credit)	$	(342)	$	1,268	$	(1,287)	$	(918)

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 for the three and six months ended June 30, 2020, was $900,000 and $1.9 million, respectfully. The Company's net periodic benefit cost for these plans for the three and six months ended June 30, 2019, was $1.1 million and $2.2 million, respectfully. The components of net periodic benefit cost for these plans are included in other income on the Consolidated Statements of Income.