Fair value (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Recurring
Fair value, Assets	$ 203,000	$ 128,000
Net liability arising from put/call options	203,000	128,000
Recurring \| Certificate of deposit
Recurring
Fair value of net assets	2,518,493	2,500,000
Recurring \| Certificate of deposit \| Fair Value, Inputs, Level 2 [Member]
Recurring
Fair value of net assets	2,518,493	2,500,000
Recurring \| Net asset arising from put/call options
Recurring
Fair value of net assets	203,000	128,000
Recurring \| Net asset arising from put/call options \| Fair Value, Inputs, Level 3 [Member]
Recurring
Fair value of net assets	$ 203,000	$ 128,000

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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- References

No definition available.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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- Definition

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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