Retirement Benefits - Reconciliation Of Changes In Benefit Obligations And Fair Value Of Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CHANGE IN PLAN ASSETS
Fair value of plan assets at January 1	$ 117,112
Fair value of plan assets at December 31	132,717	$ 117,112
COMPONENTS ON THE CONSOLIDATED BALANCE SHEETS
Other noncurrent liabilities	(87,478)	(80,667)
Pension Benefits
CHANGE IN BENEFIT OBLIGATION
Other	276
Pension Benefits | U.S.
CHANGE IN BENEFIT OBLIGATION
Obligation at January 1	85,175	91,335
Service cost	653	886	$ 976
Interest cost	2,796	2,634	2,677
Plan amendments	0	0
Benefits paid	(3,520)	(5,171)
Actuarial loss (gain)	16,931	(4,497)
Currency translation	0	0
Settlements	(4,826)	(12)
Curtailments	(1,538)	0
Acquisition/Divestiture	0	0
Other		0
Obligation at December 31	95,947	85,175	91,335
CHANGE IN PLAN ASSETS
Fair value of plan assets at January 1	83,580	76,041
Actual return on plan assets	17,446	2,070
Employer contributions	733	10,652
Benefits paid	(3,520)	(5,171)
Currency translation	0	0
Settlements	(4,826)	0
Acquisition/Divestiture	0	0
Other	0	(12)
Fair value of plan assets at December 31	93,413	83,580	76,041
Funded status at December 31	(2,534)	(1,595)
COMPONENTS ON THE CONSOLIDATED BALANCE SHEETS
Other noncurrent assets	1,921	3,058
Current liabilities	(564)	(556)
Other noncurrent liabilities	(3,891)	(4,097)
Net liability at December 31	(2,534)	(1,595)
Pension Benefits | Non-U.S.
CHANGE IN BENEFIT OBLIGATION
Obligation at January 1	89,789	97,451
Service cost	1,844	2,105	1,975
Interest cost	1,440	1,389	1,283
Plan amendments	(156)	52
Benefits paid	(1,507)	(2,791)
Actuarial loss (gain)	9,903	(3,378)
Currency translation	66	(3,335)
Settlements	0	(2,313)
Curtailments	0	0
Acquisition/Divestiture	0	0
Other	637	609
Obligation at December 31	102,016	89,789	97,451
CHANGE IN PLAN ASSETS
Fair value of plan assets at January 1	33,532	36,316
Actual return on plan assets	3,406	496
Employer contributions	2,320	2,345
Benefits paid	(1,507)	(2,791)
Currency translation	916	(1,130)
Settlements	0	(2,313)
Acquisition/Divestiture	0	0
Other	637	609
Fair value of plan assets at December 31	39,304	33,532	36,316
Funded status at December 31	(62,712)	(56,257)
COMPONENTS ON THE CONSOLIDATED BALANCE SHEETS
Other noncurrent assets	14	0
Current liabilities	(1,270)	(1,174)
Other noncurrent liabilities	(61,456)	(55,083)
Net liability at December 31	(62,712)	(56,257)
Other Benefits
CHANGE IN BENEFIT OBLIGATION
Obligation at January 1	22,593	26,068
Service cost	561	668	610
Interest cost	849	810	818
Plan amendments	0	0
Benefits paid	(676)	(847)
Actuarial loss (gain)	(161)	(3,930)
Currency translation	91	(176)
Settlements	0	0
Curtailments	0	0
Acquisition/Divestiture	0	0
Other	0	0
Obligation at December 31	23,257	22,593	26,068
CHANGE IN PLAN ASSETS
Fair value of plan assets at January 1	0	0
Actual return on plan assets	0	0
Employer contributions	676	847
Benefits paid	(676)	(847)
Currency translation	0	0
Settlements	0	0
Acquisition/Divestiture	0	0
Other	0	0
Fair value of plan assets at December 31	0	0	$ 0
Funded status at December 31	(23,257)	(22,593)
COMPONENTS ON THE CONSOLIDATED BALANCE SHEETS
Other noncurrent assets	0	0
Current liabilities	(1,127)	(1,116)
Other noncurrent liabilities	(22,130)	(21,477)
Net liability at December 31	$ (23,257)	$ (22,593)