Pension Plans and Other Postretirement Benefits Reconciliation of Benefit Obligations, Plan Assets and Funded Status of Plans, as well as Summary of Significant Assumptions for Benefit Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plans
Change in plan assets:
Fair value of plan assets, beginning balance	$ 583,659
Fair value of plan assets, Ending Balance	638,149	$ 583,659
Other Postretirement Benefits
Change in benefit obligations:
Benefit obligation, beginning balance	50,390	56,647
Service cost	98	117	$ 121
Interest cost	2,197	2,168	2,340
Actuarial loss (gain)	5,445	(5,661)
Benefits paid	(3,041)	(2,881)
Benefit obligation, ending balance	55,089	50,390	56,647
Change in plan assets:
Fair value of plan assets, beginning balance	0	834
Actual return on plan assets	0	(253)
Employer contributions	3,041	2,300
Benefits paid	(3,041)	(2,881)
Fair value of plan assets, Ending Balance	0	0	834
Funded status	(55,089)	(50,390)
Current liabilities (accrued expenses)	(4,190)	(4,233)
Noncurrent liabilities (pension benefits)	(50,899)	(46,157)
Net pension liability	$ (55,089)	$ (50,390)
Weighted-average assumptions used to determine benefit obligations at December 31:
Discount rate	3.53%	4.55%
Rate of compensation increase	3.50%	3.50%
U.S. Plans | Pension Plans
Change in benefit obligations:
Benefit obligation, beginning balance	$ 635,866	$ 685,963
Service cost	730	1,043	985
Interest cost	28,199	26,804	28,614
Plan amendments	0	0
Actuarial loss (gain)	56,108	(36,844)
Benefits paid	(42,183)	(41,100)
Employee contributions	0	0
Foreign exchange gain	0	0
Settlements/curtailments	0	0
Other	0	0
Benefit obligation, ending balance	678,720	635,866	685,963
Change in plan assets:
Fair value of plan assets, beginning balance	513,075	580,396
Actual return on plan assets	82,926	(28,457)
Employer contributions	2,865	2,236
Benefits paid	(42,183)	(41,100)
Employee contributions	0	0
Foreign exchange gain (loss)	0	0
Settlements/curtailments	0	0
Other	0	0
Fair value of plan assets, Ending Balance	556,683	513,075	$ 580,396
Funded status	(122,037)	(122,791)
Current liabilities (accrued expenses)	(1,224)	(1,342)
Noncurrent liabilities (pension benefits)	(120,813)	(121,449)
Net pension liability	(122,037)	(122,791)
Prior service benefit	0	0
Net amount recognized	$ 0	$ 0
Weighted-average assumptions used to determine benefit obligations at December 31:
Discount rate	3.56%	4.59%	4.03%	4.43%
Rate of compensation increase	0.00%	0.00%
Foreign Plans | Pension Plans
Change in benefit obligations:
Benefit obligation, beginning balance	$ 240,303	$ 275,006
Service cost	3,680	3,919	$ 2,547
Interest cost	4,998	5,144	5,128
Plan amendments	0	233
Actuarial loss (gain)	21,588	(17,885)
Benefits paid	(10,088)	(9,974)
Employee contributions	133	182
Foreign exchange gain	(1,772)	(12,632)
Settlements/curtailments	(398)	(3,628)
Other	(70)	(62)
Benefit obligation, ending balance	258,374	240,303	275,006
Change in plan assets:
Fair value of plan assets, beginning balance	70,584	79,478
Actual return on plan assets	9,417	(1,593)
Employer contributions	10,572	10,700
Benefits paid	(10,088)	(9,974)
Employee contributions	133	182
Foreign exchange gain (loss)	1,316	(4,519)
Settlements/curtailments	(398)	(3,628)
Other	(70)	(62)
Fair value of plan assets, Ending Balance	81,466	70,584	$ 79,478
Funded status	(176,908)	(169,719)
Current liabilities (accrued expenses)	(5,648)	(5,772)
Noncurrent liabilities (pension benefits)	(171,260)	(163,947)
Net pension liability	(176,908)	(169,719)
Prior service benefit	224	(409)
Net amount recognized	$ 224	$ (409)
Weighted-average assumptions used to determine benefit obligations at December 31:
Discount rate	1.33%	2.15%	1.94%	2.00%
Rate of compensation increase	3.72%	3.63%