Goodwill and Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Goodwill and Identifiable Intangible Assets [Abstract]
Goodwill	$ 200		$ 200		$ 200
Intangible assets, net [Abstract]
Impairment on intangible assets			0	$ 589
Enterprise Fund [Member]
Intangible assets, net [Abstract]
Impairment on intangible assets		$ 0		$ 589
Bancroft Fund [Member]
Intangible assets, net [Abstract]
Impairment on intangible assets	0		0
Ellsworth Fund [Member]
Intangible assets, net [Abstract]
Impairment on intangible assets	0		0
Investment Advisory Contract [Member] | Enterprise Fund [Member]
Intangible assets, net [Abstract]
Identifiable intangible asset	1,300		1,300		1,300
Investment Advisory Contract [Member] | Bancroft Fund Ltd. and the Ellsworth Growth and Income Fund Ltd. [Member]
Intangible assets, net [Abstract]
Identifiable intangible asset	$ 1,600		$ 1,600		$ 1,600