Nature of Business (Details)						1 Months Ended		3 Months Ended	9 Months Ended		12 Months Ended
	Jul. 15, 2020 USD ($) day $ / shares	Dec. 31, 2019 USD ($) shares	Jun. 12, 2019 shares	Dec. 28, 2018 USD ($) extensionTerm $ / shares shares	Aug. 10, 2018 USD ($) $ / shares shares	Apr. 15, 2019 shares	Sep. 30, 2014 shares	Sep. 30, 2020 USD ($) shares	Sep. 30, 2020 USD ($) day shares	Sep. 30, 2019 shares	Dec. 31, 2018 shares	Aug. 11, 2020 USD ($) $ / shares	Nov. 11, 2019
Debt Instrument [Line Items]
Financing receivables from affiliates | $		$ 67,153,000						$ 0	$ 0
Investment, assumed value (in usd per share) | $ / shares					$ 10
Average closing price (in usd per share) | $ / shares												$ 12.50
Shares acquired (in shares) | shares		666,667
GWG common shares transferred (in shares) | shares						3,952,155
Consideration transferred | $		$ 79,000,000.0
Change of control event, ownership threshold	25.00%							25.00%	25.00%
Convertible units, automatic exchange, number of trading days | day	20
Convertible units, automatic exchange, unit price (in usd per share) | $ / shares	$ 12.75
Convertible units, automatic exchange, minimum required capital account if all units not converted | $	$ 10,000,000
Ben LP
Debt Instrument [Line Items]
Convertible units, automatic exchange, number of trading days | day									20
Common Stock
Debt Instrument [Line Items]
Issuance of stock (in shares) | shares				27,013,516			800,000	57,183	60,871	58,009
Common stock issued upon conversion of preferred stock (in shares) | shares				5,000,000
Ben LP
Debt Instrument [Line Items]
Ownership interest											89.90%
Investment (in shares) | shares				40,505,279	4,032,349
Investment owned | $		319,000,000.0										$ 57,500,000
Shares acquired (in shares) | shares			1,000,000								40,505,279
Ben LP | Merger Consideration
Debt Instrument [Line Items]
Investment (in shares) | shares				21,650,087
Ben LP | Exchange of Exchangeable Note
Debt Instrument [Line Items]
Investment (in shares) | shares				14,822,843
Affiliated Entity | Ben LP | Commercial Loan
Debt Instrument [Line Items]
Financing receivables from affiliates | $				$ 182,000,000.0	$ 200,000,000.0
Notes and interest receivable | $				$ 192,500,000
Commercial loan, number of extensions | extensionTerm				2
Commercial loan, term				5 years
Commercial loan, interest rate				5.00%
Commercial loan, interest rate, due and payable monthly				0.025
Commercial loan, interest rate, due at maturity				0.025
Affiliated Entity | Ben LP | Exchangeable Note
Debt Instrument [Line Items]
Financing receivables from affiliates | $				$ 148,200,000	$ 162,900,000
Seller Trusts and Beneficient
Debt Instrument [Line Items]
Ownership interest				89.90%
Shares acquired (in shares) | shares				40,505,279
InsurTech Holdings, LLC [Member]
Debt Instrument [Line Items]
Ownership interest													100.00%
Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Issuance of stock (in shares) | shares					5,000,000
Preferred stock, par value (in usd per share) | $ / shares					$ 0.001
Preferred stock, liquidation preference per share (in usd per share) | $ / shares					$ 10
Cash consideration | $					$ 50,000,000.0
Common stock issued upon conversion of preferred stock (in shares) | shares				5,000,000
Conversion price (in usd per share) | $ / shares				$ 10
Series A Preferred Stock | Ben LP
Debt Instrument [Line Items]
Member capital | $		$ 1,600,000,000
Seller Trust L Bonds due 2023
Debt Instrument [Line Items]
Principal amount | $				$ 366,900,000	$ 403,200,000
Interest received | $				$ 800,000
Debt, weighted average interest rate					7.50%