Operating Expenses (Tables)

12 Months Ended

Dec. 31, 2018

Operating Expenses [Abstract]

Schedule of Direct Operating Expenses

Year ended December 31,		2018		2017		2016
Ancillary and logistical service expenses	$	66,576	$	54,176	$	47,234
Employee compensation expenses		41,391		35,440		27,856
Buildings, facilities and technology expenses		9,477		8,359		7,966
Travel, advertising and promotion expenses		27,606		23,994		23,688
Other costs of services		14,008		11,220		6,552
	$	159,058	$	133,189	$	113,296

Schedule of Selling, General and Administrative Expenses

Year ended December 31,		2018		2017		2016
Employee compensation expenses	$	249,115	$	208,370	$	180,929
Buildings, facilities and technology expenses		60,930		53,151		49,219
Travel, advertising and promotion expenses		36,728		30,440		24,384
Professional fees		16,768		13,522		13,344
Other SG&A expenses		19,135		17,787		15,653
	$	382,676	$	323,270	$	283,529

Schedule of Acquisition Related Costs

Year ended December 31,		2018		2017		2016
IronPlanet:
Other acquisition-related costs	$	2,944	$	34,653	$	8,202
Other acquisitions:
Continuing employment costs		2,091		3,418		2,491
Other acquisition-related costs		58		201		1,136
	$	5,093	$	38,272	$	11,829

Schedule of Depreciation and Amortization Expenses

Year ended December 31,		2018		2017		2016
Depreciation expense	$	29,021	$	28,337	$	30,983
Amortization expense		37,593		24,357		9,878
	$	66,614	$	52,694	$	40,861