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Goodwill and Intangible Assets - Additional Information (Details) - USD ($) shares in Millions, $ in Millions					1 Months Ended		3 Months Ended				9 Months Ended		12 Months Ended
	Feb. 19, 2020	Dec. 26, 2019	Jun. 01, 2019	Sep. 04, 2018	Oct. 31, 2018	Sep. 30, 2018	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Business Acquisition [Line Items]
Amortization expense relating to intangible assets							$ 0.7		$ 0.8		$ 1.6	$ 1.3
DBOT
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage									99.00%			99.00%
Finite-lived Intangible Assets Acquired									$ 8.3
SolidOpinion, Inc ("SolidOpinion")
Business Acquisition [Line Items]
Total purchase price paid										$ 7.2
Cash paid to acquire entity										$ 2.5
Number of shares exchange	0.5									4.5
Fintalk
Business Acquisition [Line Items]
Total purchase price paid					$ 6.4	$ 7.0
Cash paid to acquire entity					1.0	1.0
Number of shares exchange			2.9
Value of capital stock issued					$ 5.4	$ 6.0
Impairment loss								$ 5.7
Grapevine Logic, Inc. ("Grapevine")
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage						65.70%
Total purchase price paid				$ 2.4
Tree Technologies
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage								51.00%					51.00%
Cash paid to acquire entity		$ 0.9
Customer Lists [Member]
Business Acquisition [Line Items]
Weighted Average Remaining Useful Life (in years)											1 year 9 months 18 days
Marketing and Distribution Agreement [Member]
Business Acquisition [Line Items]
Weighted Average Remaining Useful Life (in years)													5 years