Quarterly report pursuant to Section 13 or 15(d)

Segment Information - Narrative (Details)

v3.19.1
Segment Information - Narrative (Details)
$ in Millions
3 Months Ended
Mar. 31, 2019
USD ($)
segment
Mar. 31, 2018
USD ($)
Segment Reporting Information [Line Items]    
Number of reportable segments 4  
Number of operating segments 4  
NSP Americas; NSP Russia, Central and Eastern Europe; and NSP China    
Segment Reporting Information [Line Items]    
Number of operating segments 3  
Synergy WorldWide    
Segment Reporting Information [Line Items]    
Number of operating segments 1  
Selling, General and Administrative Expenses | NSP China    
Segment Reporting Information [Line Items]    
Selling expense | $ $ 2.2 $ 1.5