Summary of Significant Accounting Policies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Institution	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Mar. 31, 2014 USD ($)
Activity under August 2013 contract settlement [Roll Forward]
Deferred Revenue, beginning of year	$ 2,500	$ 4,000	$ 3,000
Payment received	0	0	2,500
Deferred revenue amount recognized	0	1,500	1,500
Deferred Revenue, end of year	0	2,500	4,000
Royalty Expense [Abstract]
Royalties expense as a result of royalty agreement with Leidos	$ 0	$ 0	$ 884
Prepaid Expense and Other Assets, Current [Abstract]
Prepayment of facility lease for corporate promotional and marketing purposes				$ 4,000
Lease term	10 years
Concentration of Credit Risk and Others Risks and Uncertainties [Abstract]
Number of financial institutions holding company's cash | Institution	2
Income Taxes [Abstract]
Corporate federal tax rate	21.00%	35.00%	35.00%
Stock-Based Compensation [Abstract]
Option vesting term	4 years
Minimum [Member]
Property and Equipment [Abstract]
Useful lives	5 years
Intangible Assets [Abstract]
Estimated useful lives	3 years
Maximum [Member]
Property and Equipment [Abstract]
Useful lives	7 years
Intangible Assets [Abstract]
Estimated useful lives	15 years
Income Taxes [Abstract]
Corporate federal tax rate		35.00%
ASU Topic 606 [Member]
Activity under August 2013 contract settlement [Roll Forward]
ASU 606 Adjustment	$ (2,500)	$ 0	$ 0
New Accounting Pronouncements [Abstract]
Cumulative effect adjustments		(2,500)
ASU Topic 606 [Member] | Deferred Revenue [Member]
New Accounting Pronouncements [Abstract]
Cumulative effect adjustments		(2,500)
ASU Topic 606 [Member] | Accumulated Deficit [Member]
New Accounting Pronouncements [Abstract]
Cumulative effect adjustments		$ (2,500)
Highly Liquid Debt Investments [Member] | Maximum [Member]
Investments [Abstract]
Contractual maturities of investment securities	2 years
2013 to 2016 [Member]
Deferred Revenue [Abstract]
Total contractual payments received	$ 10,000