Employee Pension Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Summary of net periodic benefit cost
Interest cost	$ 948	$ 883	$ 2,844	$ 2,649
Expected return on plan assets	(1,043)	(1,077)	(3,129)	(3,231)
Amortization of net loss	463	513	1,389	1,539
Other	225	213	675	639
Net periodic benefit cost	593	$ 532	1,779	1,596
Company contribution			3,300	$ 2,100
Expected contributions remainder of current fiscal year	$ 1,300		$ 1,300