Acquisitions and Dispositions - Acquisitions (Details) - The Other Art Fair [Member]
$ in Millions
Jul. 07, 2016
GBP (£)
Jul. 07, 2016
USD ($)
Business Acquisition [Line Items]    
Purchase consideration, cash £ 1,100,000 $ 1.5
Deferred consideration £ 315,000  
Consideration payable, term 3 years 3 years