Joint Ventures (Summarized Information for Joint Ventures) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Net sales	$ 14,907	$ 12,846	$ 28,232	$ 24,270
Gross profit	5,608	4,706	11,081	9,142
Net income	$ 3,609	$ 1,932	$ 5,622	$ 3,952

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

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