Employee benefit plans (Tables)

9 Months Ended

Sep. 30, 2016

Employee benefit plans

Components of net periodic benefit cost

	Pension Benefits
Three Months Ended September 30,	2016		2015
Components of net periodic pension cost:
Interest cost	$	166	$	174
Expected return on plan assets		(223)		(233)
Amortization of unrecognized net gain		52		50
Net periodic other benefit cost	$	(5)	$	(9)
	Pension Benefits
Nine Months Ended September 30,	2016		2015
Components of net periodic pension cost:
Interest cost	$	499	$	522
Expected return on plan assets		(670)		(699)
Amortization of unrecognized net gain		156		150
Net periodic other benefit cost	$	(15)	$	(27)