Other non-current assets (Narrative) (Details) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($)
Loans receivable	$ 4,870
Financing Receivable [Member]
Loans receivable	$ 5,797
Financing Receivable [Member] \| Minimum [Member]
Term of financing lending arrangement	2 years
Financing Receivable [Member] \| Maximum [Member]
Term of financing lending arrangement	4 years
Financing Receivable [Member] \| Other Current Assets [Member]
Loans receivable	$ 927
Cura Classis Entities [Member]
Percentage of ownership interest	48.00%

Period between issuance and maturity of financing receivable, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

No definition available.

+ Details

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

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- Definition

Amount, after allowance for credit loss, of financing receivable, classified as noncurrent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-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

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