Equity Method Investments - Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2019
Schedule of Equity Method Investments [Line Items]
Revenues	$ 68,789	$ 24,010		$ 102,346	$ 49,227
Net loss				(70,215)	(35,945)
Net gain (loss) attributable to Ben LP common unitholders	(18,136)	(25,609)		(67,520)	(44,519)
GWG portion of net earnings (loss)	$ (1,318)	$ 600		$ (2,848)	$ (1,327)
Ben LP
Schedule of Equity Method Investments [Line Items]
GWG portion of net earnings (loss)			$ 600			$ (1,327)
Ben LP
Schedule of Equity Method Investments [Line Items]
Revenues			15,805			41,111
Net loss			(4,397)			(46,041)
Net gain (loss) attributable to Ben LP common unitholders			$ 673			$ (12,519)