Marketable Securities - Details of Marketable Securities (Details) - IronNet [Member] - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Marketable Securities [Line Items]
Fair Value	$ 22,815	$ 16,167
Basis	44,852	38,993
Cumulative Unrealized (Loss) Gain	(22,037)	(22,826)
Put Options [Member]
Marketable Securities [Line Items]
Fair Value	1,088	1,245
Basis	408	489
Cumulative Unrealized (Loss) Gain	680	756
IronNet Securities [Member]
Marketable Securities [Line Items]
Fair Value	5,985	6,351
Basis	28,044	29,185
Cumulative Unrealized (Loss) Gain	(22,059)	(22,834)
Equity Funds and Other Securities [Member]
Marketable Securities [Line Items]
Fair Value	16,830	9,816
Basis	16,808	9,808
Cumulative Unrealized (Loss) Gain	22	8
Common Stock [Member]
Marketable Securities [Line Items]
Fair Value	4,897	5,106
Basis	27,636	28,696
Cumulative Unrealized (Loss) Gain	$ (22,739)	$ (23,590)