Contract assets and liabilities (Details 5) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Contract assets and liabilities
Trading and manufacturing	$ 9,332	$ 9,619	$ 9,476
Engineering	5,617	11,769	3,881
Revenue	$ 14,949	$ 21,388	$ 13,357

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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+ Details