Description of Business and Summary of Significant Accounting Policies (Warranties) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)
Changes in the product warranty liability
Balance at the beginning of the period	$ 2,032
Warranty costs accrued	2,452
Warranty claims	(2,375)
Balance at the end of the period	$ 2,109
Alternate
Product Warranty
Product warranty period	3 years
Minimum
Product Warranty
Product warranty period	2 years
Maximum
Product Warranty
Product warranty period	10 years