Description of Business and Summary of Significant Accounting Policies (Warranties) (Details)
$ in Thousands
3 Months Ended
Mar. 31, 2018
USD ($)
Changes in the product warranty liability  
Balance at the beginning of the period $ 2,032
Warranty costs accrued 1,189
Warranty claims (854)
Balance at the end of the period $ 2,367
Alternate  
Product Warranty  
Product warranty period 3 years
Minimum  
Product Warranty  
Product warranty period 2 years
Maximum  
Product Warranty  
Product warranty period 10 years