Investment in Securities, Investment in Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Securities carried at FVTNI [Abstract]
Cost	$ 44,493	$ 40,323
Fair Value	32,322	33,789
Common Stock [Member]
Securities carried at FVTNI [Abstract]
Cost	41,356	38,865
Fair Value	29,270	32,414
Foreign Government Obligations [Member]
Securities carried at FVTNI [Abstract]
Cost	1,895	0
Fair Value	1,877	0
Open-end Funds [Member]
Securities carried at FVTNI [Abstract]
Cost	753	44
Fair Value	675	38
Closed-end Funds [Member]
Securities carried at FVTNI [Abstract]
Cost	489	1,414
Fair Value	$ 500	$ 1,337