Joint Ventures (Summarized Information for Joint Ventures) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Net sales	$ 15,216	$ 14,020	$ 43,466	$ 38,653
Gross profit	6,119	5,463	16,897	14,832
Net income	$ 3,284	$ 2,768	$ 8,906	$ 6,718

The amount of net income (loss) reported by an equity method investment of the entity.

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