Retirement Plans - Reconciliation of Benefit Obligation, Plan Assets, and Funded Status (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in plan assets:
Beginning Balance	$ 286,539
Ending Balance	259,752	$ 286,539
Defined Benefit Plan, Benefit Obligation, Benefits Paid	$ (157)	$ (165)
Post-Retirement Life Insurance Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.26%	3.59%	4.10%
Retirement Plans
Defined Benefit Plan, Accumulated Benefit Obligation	$ 4,595	$ 5,134
Change in projected benefit obligation:
Beginning Balance	5,134	4,952
Service cost	2	2	$ 3
Interest cost	156	161	207
Actuarial (gain) loss	(540)	184
Ending Balance	4,595	5,134	4,952
Change in plan assets:
Beginning Balance	0	0
Actual return on assets	0	0
Company contributions	157	165
Foreign exchange impact	0	0
Ending Balance	0	0	$ 0
Funded status (plan assets less projected benefit obligations)	(4,595)	(5,134)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	$ (157)	$ (165)
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.30%	3.63%	4.16%
Retirement Plans
Defined Benefit Plan, Accumulated Benefit Obligation	$ 205,319	$ 228,934
Change in projected benefit obligation:
Beginning Balance	228,934	247,276
Service cost	0	0	$ 87
Interest cost	7,123	8,273	11,024
Actuarial (gain) loss	(15,957)	12,562
Foreign exchange impact	0	0
Ending Balance	205,319	228,934	247,276
Change in plan assets:
Beginning Balance	284,762	292,044
Actual return on assets	(11,757)	31,559
Company contributions	103	336
Foreign exchange impact	0	0
Ending Balance	258,327	284,762	$ 292,044
Funded status (plan assets less projected benefit obligations)	53,008	55,828
Defined Benefit Plan, Benefit Obligation, Benefits Paid	$ (14,781)	$ (39,177)
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	1.13%	1.38%	1.13%
Retirement Plans
Defined Benefit Plan, Accumulated Benefit Obligation	$ 1,936	$ 2,535
Change in projected benefit obligation:
Beginning Balance	3,140	2,866
Service cost	43	48	$ 51
Interest cost	42	34	46
Actuarial (gain) loss	287	164
Foreign exchange impact	(87)	238
Ending Balance	2,756	3,140	2,866
Change in plan assets:
Beginning Balance	1,777	1,523
Actual return on assets	67	17
Company contributions	300	319
Foreign exchange impact	(50)	128
Ending Balance	1,425	1,777	$ 1,523
Funded status (plan assets less projected benefit obligations)	(1,331)	(1,363)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	$ (669)	$ (210)