Other non-current assets (Narrative) (Details) - USD ($)	6 Months Ended
Jun. 30, 2021	Dec. 31, 2020
Loans receivable	$ 8,355,000	$ 5,797,000
Trade and Other Receivables [Member]
Loans receivable	$ 4,114,000	$ 927,000
Financing Receivable [Member] \| Minimum [Member]
Term of financing lending arrangement	1 year
Financing Receivable [Member] \| Maximum [Member]
Term of financing lending arrangement	4 years

Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919230-210447

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant