Retirement Benefits - Reconciliation Of Changes In Benefit Obligations And Fair Value Of Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CHANGE IN PLAN ASSETS
Fair value of plan assets at January 1	$ 112,505
Fair value of plan assets at December 31	117,112	$ 112,505
Other noncurrent liabilities	(80,667)	(99,646)
Pension Benefit Plan
CHANGE IN BENEFIT OBLIGATION
Other	0
Pension Benefit Plan | U.S. Plans
CHANGE IN BENEFIT OBLIGATION
Obligation at January 1	91,335	90,256
Service cost	886	976	$ 1,016
Interest cost	2,634	2,677	3,043
Plan amendments	0	0
Benefits paid	(5,171)	(6,258)
Actuarial loss (gain)	(4,497)	3,684
Currency translation	0	0
Settlements	(12)	0
Acquisition/Divestiture	0	0
Other		0
Obligation at December 31	85,175	91,335	90,256
CHANGE IN PLAN ASSETS
Fair value of plan assets at January 1	76,041	73,688
Actual return on plan assets	2,070	5,046
Employer contributions	10,652	3,565
Benefits paid	(5,171)	(6,258)
Currency translation		0
Settlements		0	(11,000)
Acquisition/Divestiture		0
Other	(12)	0
Fair value of plan assets at December 31	83,580	76,041	73,688
Funded status at December 31	(1,595)	(15,294)
Other noncurrent assets	3,058	0
Current liabilities	(556)	(658)
Other noncurrent liabilities	(4,097)	(14,636)
Net liability at December 31	(1,595)	(15,294)
Pension Benefit Plan | Non-U.S. Plans
CHANGE IN BENEFIT OBLIGATION
Obligation at January 1	97,451	87,764
Service cost	2,105	1,975	1,627
Interest cost	1,389	1,283	1,429
Plan amendments	52	0
Benefits paid	(2,791)	(1,942)
Actuarial loss (gain)	(3,378)	(15)
Currency translation	(3,335)	9,323
Settlements	(2,313)	(2,452)
Acquisition/Divestiture	0	(482)
Other	609	1,997
Obligation at December 31	89,789	97,451	87,764
CHANGE IN PLAN ASSETS
Fair value of plan assets at January 1	36,316	32,586
Actual return on plan assets	496	1,792
Employer contributions	2,345	2,702
Benefits paid	(2,791)	(1,942)
Currency translation	(1,130)	2,446
Settlements	(2,313)	(2,452)
Acquisition/Divestiture		0
Other	609	1,184
Fair value of plan assets at December 31	33,532	36,316	32,586
Funded status at December 31	(56,257)	(61,135)
Other noncurrent assets	0	0
Current liabilities	(1,174)	(1,159)
Other noncurrent liabilities	(55,083)	(59,976)
Net liability at December 31	(56,257)	(61,135)
Other Benefit Plans
CHANGE IN BENEFIT OBLIGATION
Obligation at January 1	26,068	24,636
Service cost	668	610	601
Interest cost	810	818	811
Plan amendments		0
Benefits paid	(847)	(738)
Actuarial loss (gain)	(3,930)	592
Currency translation	(176)	150
Settlements		0
Acquisition/Divestiture		0
Other		0
Obligation at December 31	22,593	26,068	24,636
CHANGE IN PLAN ASSETS
Fair value of plan assets at January 1	0	0
Actual return on plan assets	0	0
Employer contributions	847	738
Benefits paid	(847)	(738)
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	(22,593)	(26,068)
Other noncurrent assets	0	0
Current liabilities	(1,116)	(1,034)
Other noncurrent liabilities	(21,477)	(25,034)
Net liability at December 31	$ (22,593)	$ (26,068)