Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Entity-Wide Disclosure (Schedule of Net Sales by Geographic Area) (Details)

v3.8.0.1
Entity-Wide Disclosure (Schedule of Net Sales by Geographic Area) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Segment Reporting Information [Line Items]      
Net sales $ 668,362 $ 672,458 $ 695,995
Americas (primarily the United States) [Member]      
Segment Reporting Information [Line Items]      
Net sales 413,326 411,536 425,569
Europe and Middle East [Member]      
Segment Reporting Information [Line Items]      
Net sales 148,279 137,924 148,169
Asia Pacific [Member]      
Segment Reporting Information [Line Items]      
Net sales $ 106,757 $ 122,998 $ 122,257