Goodwill (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2014	Dec. 31, 2018
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Goodwill	$ 2,791,000	$ 2,800,000	$ 2,791,000
Goodwill impairment	$ 0
TPI, BEM And NB [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Aggregate consideration		$ 5,500,000