Employee Pension Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Summary of net periodic benefit cost
Interest cost	$ 975	$ 1,053	$ 2,925	$ 3,159
Expected return on plan assets	(1,088)	(1,203)	(3,264)	(3,609)
Amortization of net loss	456	427	1,368	1,281
Other	213	150	639	450
Net periodic benefit cost	$ 556	$ 427	1,668	1,281
Company contribution			2,000	$ 1,300
Expected contributions remainder of current fiscal year			$ 600