Equity Method Investments - Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2019
Schedule of Equity Method Investments [Line Items]
Total revenues	$ 28,513	$ 22,211		$ 130,859	$ 71,439
Net loss				(147,540)	(56,348)
Net gain (loss) attributable to Ben LP common unitholders	(68,149)	(24,635)		(135,669)	(69,154)
GWG portion of net earnings (loss)	$ (1,431)	$ 956		$ (4,279)	$ (371)
Ben LP
Schedule of Equity Method Investments [Line Items]
GWG portion of net earnings (loss)			$ 956			$ (371)
Ben LP
Schedule of Equity Method Investments [Line Items]
Total revenues			28,151			69,262
Net loss			9,696			(36,345)
Net gain (loss) attributable to Ben LP common unitholders			$ 1,080			$ (11,439)