Restructuring Charges (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) number_of_employees	Dec. 31, 2016 USD ($) number_of_employees	Dec. 31, 2015 USD ($) number_of_employees
Restructuring Cost and Reserve [Line Items]
Number of employees reduced in connection with workforce of certain facilities | number_of_employees	163	582	672
2017 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs	$ 2,172
Other exit costs	531
Facility lease obligations	$ 264
2016 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs		$ 3,630
Other exit costs		$ 977
2015 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs			$ 2,542
Other exit costs			3,301
Facility lease obligations			$ 2,462
Americas [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees reduced in connection with workforce of certain facilities | number_of_employees	160	370	223
Americas [Member] | 2017 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs	$ 1,985
Other exit costs	531
Facility lease obligations	$ 264
Americas [Member] | 2016 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs		$ 1,726
Other exit costs		$ 924
Americas [Member] | 2015 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs			$ 1,564
Other exit costs			3,099
Facility lease obligations			$ 2,462
Asia [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees reduced in connection with workforce of certain facilities | number_of_employees	3	212	438
Asia [Member] | 2017 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs	$ 187
Number of employees reduced in connection with workforce of certain facilities | number_of_employees	3
Other exit costs	$ 0
Facility lease obligations	$ 0
Asia [Member] | 2016 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs		$ 1,904
Other exit costs		0
Asia [Member] | 2015 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs			$ 506
Other exit costs			0
Facility lease obligations			$ 0
Europe [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees reduced in connection with workforce of certain facilities | number_of_employees			11
Europe [Member] | 2016 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs		0
Other exit costs		$ 53
Europe [Member] | 2015 [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination costs			$ 472
Other exit costs			202
Facility lease obligations			$ 0