Other non-current assets (Narrative) (Details) - USD ($)	6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Mar. 17, 2022	Dec. 31, 2021
Loans receivable	$ 11,749,000			$ 7,267,000
Right-of-use assets	134,219,000			114,414,000
Maltby auction site
Right-of-use assets	9,020,000
Bolton Properties Sale Leaseback Transaction [Member]
Right-of-use assets		$ 16,587,000	$ 16,587,000
Non-current Loans Receivable [Member]
Loans receivable	7,199,000			0
Trade and Other Receivables [Member]
Loans receivable	$ 4,550,000			$ 7,267,000
Financing Receivable [Member] | Minimum [Member]
Term of financing lending arrangement	1 year
Financing Receivable [Member] | Maximum [Member]
Term of financing lending arrangement	4 years