Investments in Associated Companies - Summarized Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Manufacturing And Services [Member]
Equity Method Investment Summarized Financial Information Abstract
Current Assets	$ 43,581	$ 37,683
Non-current Assets	990	936
Current Liabilities	29,632	24,858
Non-current Liabilities	1,685	1,457
Equity Method Investment Summarized Financial Information Income Statement [Abstract]
Revenue	43,875	42,555	$ 41,448
Gross Profit	12,983	13,440	13,082
Income Before Income Taxes	2,494	2,900	2,289
Net Income	1,874	1,471	1,210
Captive Insurance Company [Member]
Equity Method Investment Summarized Financial Information Abstract
Total Assets	103,705	120,154
Total Liabilities	53,049	54,258
Equity Method Investment Summarized Financial Information Income Statement [Abstract]
Revenue	5,841	14,042	5,632
Income Before Income Taxes	3,688	11,705	5,622
Net Income	$ 2,954	$ 7,788	$ 5,148