Pension Benefits (Tables)

6 Months Ended

Jun. 30, 2019

Defined Benefit Plan [Abstract]

Components of the net periodic benefit cost for the pension plans [Table Text Block]

Components of Net Periodic Benefit Cost for the Pension Plans

	For the Three Months Ended June 30,						For the Six Months Ended June 30,
	2019			2018			2019			2018
	(in thousands)
Components of net periodic benefit cost:
Service cost	$	1,108		$	1,705		$	2,791		$	3,365
Interest cost	739			637			1,395			1,310
Expected return on plan assets that reduces periodic pension benefit cost	(321		)	(370		)	(787		)	(931		)
Amortization of prior service cost	5			5			9			9
Amortization of net actuarial loss	147			340			479			664
Net periodic benefit cost	$	1,678		$	2,317		$	3,887		$	4,417