Segment and Geographic Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			2
Number of reportable segments | segment			2
Industry Segment Information
Equipment trading revenues	$ 26,094,000	$ 25,796,000	$ 58,377,000	$ 66,833,000
Expenses	$ 183,590,000	$ 172,446,000	546,794,000	515,856,000
Intersegment Eliminations
Industry Segment Information
Equipment trading revenues			0	0
Expenses			$ 0	$ 0