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Percentage of voting equity interests acquired in a business combination achieved in stages, including equity interests in the acquiree held by the acquirer immediately before the acquisition date and acquired at the acquisition date.

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Amount of common stock allocated to investors to buy shares of a new issue of common stock before they are offered to the public. When stock is sold on a subscription basis, the issuer does not initially receive the total proceeds. In general, the issuer does not issue the shares to the investor until it receives the entire proceeds.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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Long-term Investments - Additional Information (Details)							3 Months Ended		7 Months Ended		9 Months Ended
	Jul. 26, 2021 USD ($)	Jun. 11, 2021 USD ($)	Apr. 20, 2021 USD ($) $ / shares shares	Mar. 03, 2021 USD ($) $ / shares shares	Nov. 19, 2020 USD ($) shares	Oct. 22, 2020 USD ($) $ / shares shares	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Aug. 13, 2021 USD ($)	Aug. 13, 2021 EUR (€)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 EUR (€)	Aug. 13, 2021 EUR (€)	Aug. 01, 2021 USD ($) shares	Aug. 01, 2021 EUR (€) shares	Apr. 21, 2021	Mar. 31, 2021	Mar. 03, 2021 EUR (€) € / shares	Jan. 28, 2021 USD ($)	Jan. 28, 2021 EUR (€)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 EUR (€)
Long-term Investments
Equity securities, FV-NI, cost					$ 1,300,000
Equity method investments							$ 25,027,000				$ 25,027,000											$ 3,783,000
Initial investment											24,914,000
Solectrac
Long-term Investments
Payments to acquire investment						$ 1,300,000
Number of shares acquired (in shares) \| shares					1,300,000
Equity method investment, ownership percentage																		24.30%
Equity method investments							0				0											$ 2,556,000
Initial investment											0
Non Marketable Equity Investments
Long-term Investments
Impairment loss with respect to one non-marketable equity investment							$ 1,500,000	$ 0			$ 1,500,000	$ 0
Grapevine Logic, Inc. ("Grapevine")
Long-term Investments
Percentage of ownership interest			100.00%
FNL Technologies
Long-term Investments
Percentage of ownership interest							29.00%				29.00%		29.00%				29.00%
Solectrac
Long-term Investments
Cash paid at closing, including working capital estimates		$ 17,745,000
Equity ownership percentage		100.00%
Solectrac
Long-term Investments
Number of shares acquired (in shares) \| shares						1,400,000
Percentage of shares acquired						15.00%
Consideration per share (in dollars per share) \| $ / shares						$ 0.91
Percentage of battery-powered electric tractors dealt					100.00%
Solectrac \| Solectrac
Long-term Investments
Percentage of battery-powered electric tractors dealt		100.00%
FNL Technologies
Long-term Investments
Issuance of shares of Ideanomics common stock to investee (in shares) \| shares			100,000
Received share of common stock (in shares) \| shares			600,000
Equity conversion of common stock (in shares) \| shares			30,902
FNL Technologies \| Common Stock
Long-term Investments
Subscription price (in dollars per share) \| $ / shares			$ 8.09
Amount converted for future equity			$ 250,000
FNL Technologies \| Cash
Long-term Investments
Equity method investments			$ 2,900,000
Prettl Electronics Automotive
Long-term Investments
Investments															$ 8,500,000	€ 7,500,000
Preferred stock, investment (in shares) \| shares															11,175	11,175
Energica Investment
Long-term Investments
Payments to acquire investment				$ 13,600,000															€ 10,100,000
Equity method investment, ownership percentage				20.00%															20.00%
Common stock issued through equity method (in shares) \| shares				6,100,000
Subscription price (in dollars per share) \| (per share)				$ 2.21															€ 1.78
Share selling, restriction period				90 days
Investment net assets							$ 10,900,000				$ 10,900,000
Aggregate market value of shares owned							$ 22,500,000				$ 22,500,000
MDI Fund
Long-term Investments
Payments to acquire investment	$ 25,000,000
Initial investment	$ 600,000
TM2 \| Non Marketable Equity Investments
Long-term Investments
Payments to acquire investment									$ 5,900,000					€ 5,000,000						$ 1,800,000	€ 1,500,000
Increase in investment									$ 4,100,000	€ 3,500,000
Equity financing threshold \| €																					€ 5,000,000
Pre-investment valuation																							$ 11,100,000	€ 10,000,000
Current investment valuation \| €													€ 11,000,000