Goodwill and Intangible Assets (Changes in Carrying Amount of Goodwill by Segment) (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Goodwill [Roll Forward]  
Beginning Balance $ 98,227
Foreign currency translation adjustment (8,597)
Arlon acquisition 85,379
Ending Balance 175,009
Printed Circuit Materials [Member]  
Goodwill [Roll Forward]  
Beginning Balance 0
Foreign currency translation adjustment 0
Arlon acquisition 51,862
Ending Balance 51,862
High Performance Foams [Member]  
Goodwill [Roll Forward]  
Beginning Balance 23,565
Foreign currency translation adjustment (275)
Arlon acquisition 33,517
Ending Balance 56,807
Power Electronics Solutions [Member]  
Goodwill [Roll Forward]  
Beginning Balance 72,438
Foreign currency translation adjustment (8,322)
Arlon acquisition 0
Ending Balance 64,116
Other [Member]  
Goodwill [Roll Forward]  
Beginning Balance 2,224
Foreign currency translation adjustment 0
Arlon acquisition 0
Ending Balance $ 2,224