Goodwill (Schedule of Carrying Value Goodwill) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Goodwill	$ 92,307	$ 91,234
Core Auction [Member]
Goodwill	58,113	53,303
EquipmentOne [Member]
Goodwill	14,357	$ 37,931
Mascus International Holdings BV [Member]
Goodwill	$ 19,837

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant