Financial instruments (Tables)

12 Months Ended

Dec. 31, 2018

Investments, All Other Investments [Abstract]

Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]

The following table presents the Company’s fair value hierarchy for assets and liabilities measured at fair value as of December 31, 2018 and 2017:

	December 31, 2018
	Level 1		Level 2		Level 3		Total
Assets:
Recurring
Net asset arising from put/call options	$	-	$	-	$	24,000	$	24,000

	December 31, 2017
	Level 1		Level 2		Level 3		Total
Assets:
Recurring
Net asset arising from put/call options	$	-	$	-	$	280,000	$	280,000

Fair Value Measurements, Nonrecurring [Table Text Block]

The activity for the Level 3 asset for the year ended December 31, 2018:

Net asset arising from put/call options
Balance as of December 31, 2017(1)	$	280,000
Unrealized loss		256,000
Balance as of December 31, 2018(1)	$	24,000

(1) The net asset arising from the put/call options is included in other assets in the accompanying consolidated balance sheets as of December 31, 2018 and 2017.