Segmented information (Schedule of Revenue and Net income by Segment) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting [Line Items]
Revenue	$ 484,546,000	$ 396,361,000	$ 878,467,000	$ 727,916,000
Selling, general and administrative expenses ("SG&A")	144,277,000	109,560,000	270,883,000	223,799,000
Acquisition-related costs	3,399,000	3,049,000	13,036,000	5,971,000
Depreciation and amortization expenses ("D&A")	24,298,000	21,935,000	48,523,000	43,005,000
Foreign exchange loss (gain)	(158,000)	151,000	(322,000)	428,000
Total operating expenses	393,026,000	307,019,000	723,927,000	594,140,000
Gain on disposition of property, plant and equipment ("PPE")	(347,000)	(175,000)	(170,167,000)	(243,000)
Operating income	91,867,000	89,517,000	324,707,000	134,019,000
Interest expense	(18,463,000)	(8,867,000)	(39,149,000)	(17,813,000)
Change in fair value of derivatives, net			1,263,000
Debt extinguishment costs			(4,792,000)
Other income, net	1,639,000	1,196,000	2,559,000	2,198,000
Income tax expense	(21,632,000)	(21,065,000)	(57,868,000)	(29,484,000)
Net income	53,411,000	60,781,000	231,512,000	88,920,000
Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	484,546,000	396,361,000	878,467,000	727,916,000
Selling, general and administrative expenses ("SG&A")	144,277,000	109,560,000	270,883,000	223,799,000
Segment profit	119,059,000	114,477,000	215,777,000	183,180,000
Acquisition-related costs	3,399,000	3,049,000	13,036,000	5,971,000
Depreciation and amortization expenses ("D&A")	24,298,000	21,935,000	48,523,000	43,005,000
Foreign exchange loss (gain)	(158,000)	151,000	(322,000)	428,000
Total operating expenses	393,026,000	307,019,000	723,927,000	594,140,000
Gain on disposition of property, plant and equipment ("PPE")	347,000	175,000	170,167,000	243,000
Operating income	91,867,000	89,517,000	324,707,000	134,019,000
Interest expense	(18,463,000)	(8,867,000)	(39,149,000)	(17,813,000)
Change in fair value of derivatives, net			1,263,000
Other income, net	1,639,000	1,196,000	2,559,000	2,198,000
Income tax expense	(21,632,000)	(21,065,000)	(57,868,000)	(29,484,000)
Net income	53,411,000	60,781,000	231,512,000	88,920,000
Auctions and Marketplaces [Member] | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	433,035,000	356,281,000	783,099,000	653,877,000
Selling, general and administrative expenses ("SG&A")	125,535,000	99,215,000	234,346,000	201,996,000
Segment profit	102,344,000	100,867,000	186,441,000	160,631,000
Other Reporting Unit [Member] | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	51,511,000	40,080,000	95,368,000	74,039,000
Selling, general and administrative expenses ("SG&A")	18,742,000	10,345,000	36,537,000	21,803,000
Segment profit	16,715,000	13,610,000	29,336,000	22,549,000
Service Revenues [Member]
Segment Reporting [Line Items]
Revenue	286,502,000	252,748,000	531,363,000	458,778,000
Direct expenses	45,039,000	41,301,000	84,054,000	79,167,000
Service Revenues [Member] | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	286,502,000	252,748,000	531,363,000	458,778,000
Direct expenses	45,039,000	41,301,000	84,054,000	79,167,000
Service Revenues [Member] | Auctions and Marketplaces [Member] | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	234,991,000	212,668,000	435,995,000	384,739,000
Direct expenses	28,985,000	25,176,000	54,559,000	49,480,000
Service Revenues [Member] | Other Reporting Unit [Member] | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	51,511,000	40,080,000	95,368,000	74,039,000
Direct expenses	16,054,000	16,125,000	29,495,000	29,687,000
Commissions
Segment Reporting [Line Items]
Revenue	136,403,000	129,334,000	252,778,000	233,309,000
Commissions | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	136,403,000	129,334,000	252,778,000	233,309,000
Commissions | Auctions and Marketplaces [Member] | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	136,403,000	129,334,000	252,778,000	233,309,000
Fees
Segment Reporting [Line Items]
Revenue	150,099,000	123,414,000	278,585,000	225,469,000
Fees | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	150,099,000	123,414,000	278,585,000	225,469,000
Fees | Auctions and Marketplaces [Member] | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	98,588,000	83,334,000	183,217,000	151,430,000
Fees | Other Reporting Unit [Member] | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	51,511,000	40,080,000	95,368,000	74,039,000
Inventory Sales Revenue [Member]
Segment Reporting [Line Items]
Revenue	198,044,000	143,613,000	347,104,000	269,138,000
Direct expenses	176,171,000	131,023,000	307,753,000	241,770,000
Inventory Sales Revenue [Member] | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	198,044,000	143,613,000	347,104,000	269,138,000
Direct expenses	176,171,000	131,023,000	307,753,000	241,770,000
Inventory Sales Revenue [Member] | Auctions and Marketplaces [Member] | Operating Segments [Member]
Segment Reporting [Line Items]
Revenue	198,044,000	143,613,000	347,104,000	269,138,000
Direct expenses	$ 176,171,000	$ 131,023,000	$ 307,753,000	$ 241,770,000