Acquisitions (Details 2) - OIE Membership Acquisition [Member] $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares
Business Acquisition [Line Items]
Revenue	$ 136,592
Net income before non-controlling interests	11,320
Net loss attributable to non-controlling interests	4,375
Net income attributable to controlling interests	$ 5,596
Net income per share (basic) | $ / shares	$ 0.74
Net income per share (diluted) | $ / shares	$ 0.69
Carbon California [Member]
Business Acquisition [Line Items]
Revenue	$ 33,256
Net income before non-controlling interests	5,232
Net loss attributable to non-controlling interests	(2,334)
Net income attributable to controlling interests	$ 7,566
Net income per share (basic) | $ / shares	$ 1.00
Net income per share (diluted) | $ / shares	$ 0.96