Employee benefit plans (Tables)

6 Months Ended

Jun. 30, 2020

Retirement Benefits [Abstract]

Schedule of net benefit costs

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)