Financial instruments (Details 1)	12 Months Ended
	Dec. 31, 2016 USD ($)	[1]
Financial Instruments [Line Items]
Balance	$ 0
Net put/call option liability - Aerex	383,000
Increase in net put/call option liability - Aerex	297,000
Balance	$ 680,000

[1] The net liability arising from the put/call options is included other liabilities in the accompanying condensed consolidated balance sheets as of December 31, 2016.