Stockholders' deficit - Options Outstanding (Details) - Options	6 Months Ended
Jun. 30, 2018 $ / shares shares
Beginning balance, options	480,000
Beginning balance, options exercise price \| $ / shares	$ 0.12
Options Exercisable, shares	480,000
Ending Balance, options	480,000
Ending Balance, options exercise price \| $ / shares	$ 0.12
Weighted Average Contractual Life, options	1 year 4 months 2 days

Number of share options (or share units) exercised during the current period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration