Pension plans and other postretirement benefits (Tables)

9 Months Ended

Sep. 30, 2018

Compensation And Retirement Disclosure [Abstract]

Net Periodic Defined Benefit Cost for Defined Benefit Plans

Net periodic defined benefit cost for defined benefit plans consisted of the following:

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended September 30
	2018			2017			2018			2017
	(In thousands)
Service cost	$	5,086			5,048			234		293
Interest cost on projected benefit obligation		18,676			19,818			573			929
Expected return on plan assets		(30,781	)		(27,131	)		—			—
Amortization of prior service cost (credit)		139			139			(1,182	)		(340	)
Amortization of net actuarial loss (gain)		10,948			7,316			(206	)		(247	)
Net periodic benefit cost	$	4,068			5,190			(581	)		635

	Pension Benefits						Other Postretirement Benefits
	Nine Months Ended September 30
	2018			2017			2018			2017
	(In thousands)
Service cost	$	15,258			15,145			703			878
Interest cost on projected benefit obligation		56,029			59,452			1,719			2,787
Expected return on plan assets		(92,344	)		(81,393	)		—			—
Amortization of prior service cost (credit)		417			418			(3,546	)		(1,019	)
Amortization of net actuarial loss (gain)		32,844			21,947			(619	)		(741	)
Net periodic benefit cost	$	12,204			15,569			(1,743	)		1,905