Share-based payments - Unrecognized Share-based Compensation Cost (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Unrecognized Share-based Compensation Cost
Total unrecognized expense	$ 24,308	$ 24,466
EDIP \| Time vesting shares
Unrecognized Share-based Compensation Cost
Unrecognized cost	$ 11,774	$ 14,234
Weighted average years over which it is expected to be recognized	2 years 7 months 28 days	3 years 4 months 6 days
ELTIP \| Time vesting shares
Unrecognized Share-based Compensation Cost
Unrecognized cost	$ 118	$ 0
Weighted average years over which it is expected to be recognized	2 years 1 month 13 days	0 years
ELTIP \| Performance vesting shares
Unrecognized Share-based Compensation Cost
Unrecognized cost	$ 12,416	$ 10,232
Weighted average years over which it is expected to be recognized	1 year 9 months 3 days	1 year 9 months

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

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- References

No definition available.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

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