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STOCK-BASED AWARDS - Stock-based Compensation Expense (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based Payment Arrangement, Expense	$ 2,623,000	$ 4,467,000	$ 8,356,000	$ 13,623,000
Medici Ventures \| Employee Stock Options
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			13,650
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	282,000		$ 282,000
tZero.com, Inc. \| Employee Stock Options
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			60,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	46,000		$ 46,000
Cost of Sales [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based Payment Arrangement, Expense	50,000	55,000	153,000	156,000
Selling and Marketing Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based Payment Arrangement, Expense	(76,000)	486,000	621,000	1,460,000
Technology [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based Payment Arrangement, Expense	460,000	1,428,000	1,822,000	4,325,000
General and Administrative Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based Payment Arrangement, Expense	$ 2,189,000	$ 2,498,000	$ 5,760,000	$ 7,682,000