SUPPLEMENTAL CONSOLIDATED BALANCE SHEETS AND STATEMENTS OF OPERATIONS INFORMATION - Schedule of Accrued Merchant and Supplier Payables (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Supplemental Consolidated Balance Sheet & Statement of Operations Information [Abstract]
Accrued merchant payables	$ 366,573	$ 371,279
Accrued supplier payables (1)	174,367	280,502
Total accrued merchant and supplier payables	$ 540,940	$ 651,781