Summary of significant accounting policies - Revenue Receivable (Details) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Summary of significant accounting policies
Credit losses	$ 0		$ 0
Bad debt expense	$ 0	$ 0	$ 0	$ 0

Amount of expense related to credit loss from transactions other than loan and lease transactions.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(11))
-URI https://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

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Balance Type:	debit
Period Type:	duration