Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands		2 Months Ended		12 Months Ended
	Mar. 13, 2020	Mar. 10, 2020	Feb. 21, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Stock [Member]
Stock Transactions [Abstract]
Number of shares of common stock sold (in shares)				1,860,483	7,510,555
ATM Agreement [Member] | Common Stock [Member]
Stock Transactions [Abstract]
Number of shares of common stock sold (in shares)				1,860,483	7,510,555
Average sales price per common share (in dollars per share)				$ 5.84	$ 3.71
Aggregate proceeds from sales of common stock				$ 10,866	$ 27,837
Sales commissions, fees and other costs associated with issuance of common stock				$ 326	$ 785
Subsequent Event [Member]
Stock Transactions [Abstract]
Options exercised (in shares)		151,308
Subsequent Event [Member] | Positive Outcome of Litigation [Member] | VirnetX Inc. v. Cisco Systems, Inc. et al. (Case 6:10-CV-00417-LED) ("Apple I") [Member]
Stock Transactions [Abstract]
Amount of final judgment with interest received	$ 454,034
Subsequent Event [Member] | ATM Agreement [Member] | Common Stock [Member]
Stock Transactions [Abstract]
Number of shares of common stock sold (in shares)			1,049,382
Average sales price per common share (in dollars per share)			$ 4.41
Aggregate proceeds from sales of common stock			$ 4,627
Sales commissions, fees and other costs associated with issuance of common stock			$ 139