Retirement Benefits - Amounts in Accumulated Other Comprehensive Income Loss Expected to be Recognized As Components of Net Periodic Benefit Cost During 2012 (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior service cost (credit)	$ (49)
Net loss	2,498
Total	2,449
Pension Benefit Plan | U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior service cost (credit)	62	$ 86
Net loss	22,478	27,789
Total	22,540	27,875
Prior service cost (credit)	15
Net loss	1,931
Total	1,946
Pension Benefit Plan | Non-U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior service cost (credit)	64	18
Net loss	12,955	17,986
Total	13,019	18,004
Prior service cost (credit)	6
Net loss	1,131
Total	1,137
Other Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior service cost (credit)	(117)	(483)
Net loss	(6,386)	(2,866)
Total	(6,503)	$ (3,349)
Prior service cost (credit)	(70)
Net loss	(564)
Total	$ (634)