Goodwill and Other Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	15 years
Gross Carrying Value	$ 87,848	$ 88,181
Accumulated Amortization	(34,173)	(30,741)
Net Carrying Amount	53,675	57,440
Non-compete agreements
Finite-Lived Intangible Assets
Gross Carrying Value	4,224	4,238
Accumulated Amortization	(3,539)	(3,100)
Net Carrying Amount	685	1,138
Patents
Finite-Lived Intangible Assets
Gross Carrying Value	372	389
Accumulated Amortization	(164)	(164)
Net Carrying Amount	208	225
Customer relationships
Finite-Lived Intangible Assets
Gross Carrying Value	37,458	37,679
Accumulated Amortization	(10,312)	(9,171)
Net Carrying Amount	27,146	28,508
Trademarks and trade names
Finite-Lived Intangible Assets
Gross Carrying Value	10,067	10,085
Accumulated Amortization	(4,504)	(4,091)
Net Carrying Amount	5,563	5,994
Technology
Finite-Lived Intangible Assets
Gross Carrying Value	35,727	35,790
Accumulated Amortization	(15,654)	(14,215)
Net Carrying Amount	$ 20,073	$ 21,575
Weighted Average
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	15 years
Weighted Average | Non-compete agreements
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	5 years	5 years
Weighted Average | Patents
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	10 years	10 years
Weighted Average | Customer relationships
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	17 years	17 years
Weighted Average | Trademarks and trade names
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	14 years	14 years
Weighted Average | Technology
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	14 years	14 years