Retirement Plans - Net Pension Income Domestic and Foreign (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension Plans
Net pension expense (income)
(Income) expense, net	$ 250	$ 77	$ 749	$ 234
UNITED STATES
Net pension expense (income)
Service cost	0	0	0	0
Interest cost	1,931	1,781	5,793	5,343
Defined Benefit Plan, Expected Return on Plan Assets, Net of Expenses	(3,046)	(3,225)	(9,140)	(9,675)
Amortization of loss	1,311	1,466	3,934	4,398
(Income) expense, net	196	22	587	66
Foreign Plan [Member]
Net pension expense (income)
Service cost	9	11	27	33
Interest cost	8	10	23	32
Defined Benefit Plan, Expected Return on Plan Assets, Net of Expenses	(4)	(6)	(13)	(19)
Amortization of loss	41	40	125	122
(Income) expense, net	$ 54	$ 55	$ 162	$ 168