Operating Segments and Geographic Information (Operations by Geographic Area) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 684,652	$ 576,996	$ 522,894
United States
Segment Reporting Information [Line Items]
Long-Lived Assets	476,560	370,964	326,199
China
Segment Reporting Information [Line Items]
Long-Lived Assets	58,205	57,404	62,728
Germany
Segment Reporting Information [Line Items]
Long-Lived Assets	113,412	114,497	101,725
Other
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 36,475	$ 34,131	$ 32,242