Employee benefit plans (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of net periodic benefit cost

The net periodic benefit cost was as follows (in thousands):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Service cost	$	1,288	$	1,032	$	2,550	$	2,111
Interest cost		86		68		169		139
Expected return on plan assets		(61)		(47)		(120)		(97)
Amortization of prior service cost		62		45		107		90
Amortization of actuarial losses		46		66		112		132
Net periodic benefit cost	$	1,421	$	1,164	$	2,818	$	2,375