Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 110	$ 99
2018	442
2019	412
2020	406
2021	406
2022	88
Recorded intangible assets
Customer Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Recorded intangible assets
Customer Lists [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period	7 years
Customer Lists [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period	10 years
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period	18 years
Software [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period	3 years
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period	15 years
Goodwill [Member]
Finite-Lived Intangible Assets [Line Items]
Recorded intangible assets
Non-compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Recorded intangible assets
Non-compete Agreements [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period	2 years
Non-compete Agreements [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period	5 years