General and Basis of Presentation (Details) $ / shares in Units, shares in Thousands, $ in Thousands				3 Months Ended
	Nov. 23, 2020 USD ($)	Nov. 19, 2020 USD ($) $ / shares shares	Nov. 12, 2020	Mar. 31, 2021 USD ($) Segment Reportingunit Installment $ / shares shares	Mar. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2020 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | Segment				1
Disaggregation of Revenue [Abstract]
Revenue				$ 55,757	$ 38,980
Components of Accounts Receivable [Abstract]
Billed accounts receivable				12,382		$ 12,060
Unbilled receivables				40,494		19,161
Allowance for doubtful accounts				(313)		(308)
Receivables - net				52,563		30,913
Components of Contract Liabilities [Abstract]
Contract liabilities				6,751		5,654
Revenue, Performance Obligation [Abstract]
Remaining performance obligation				126,800		127,700
Revenue recognized included in opening contract liabilities				2,000	2,400
Inventories [Abstract]
Gross inventory				2,700		4,200
Inventory obsolescence reserves				852		851
Software Development Costs [Abstract]
Capitalized software development costs				14,400		12,300
Amortization expense				500	$ 500
Accumulated amortization				$ 5,300		4,800
Goodwill [Abstract]
Number of reporting units | Reportingunit				3
Goodwill amortization period for income tax purposes				15 years
Antidilutive Securities Excluded from Computation of Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount | shares				4,068	1,858
Warrants exercise price (in dollars per share) | $ / shares				$ 1.665	$ 1.665
Reverse stock split			0.794
Accumulated Other Comprehensive Income [Abstract]
Cumulative foreign currency translation loss				$ (95)		(63)
Cumulative actuarial gain on pension liability adjustment				107		107
Accumulated other comprehensive income				12		$ 44
Exchangeable Redeemable Preferred Stock [Member]
Initial Public Offering of Common Stock [Abstract]
Conversion of preferred stock to common stock	$ 108,900
Firm Fixed-Price [Member]
Disaggregation of Revenue [Abstract]
Revenue				49,141	$ 31,662
Time-and-Materials [Member]
Disaggregation of Revenue [Abstract]
Revenue				3,030	3,825
Cost Plus Fixed Fee [Member]
Disaggregation of Revenue [Abstract]
Revenue				$ 3,586	3,493
Minimum [Member]
Software Development Costs [Abstract]
Software development estimated useful life				2 years
Initial Public Offering [Member]
Initial Public Offering of Common Stock [Abstract]
Number of shares issued (in shares) | shares		17,200
Share price (in dollars per share) | $ / shares		$ 17.00
Net proceeds from initial public offering		$ 272,800
Repayment of senior term loan and subordinated debt		21,000
Initial Public Offering [Member] | Exchangeable Redeemable Preferred Stock [Member]
Initial Public Offering of Common Stock [Abstract]
Conversion of preferred stock to common stock		108,900
Initial Public Offering [Member] | Telos ID [Member] | Class B Common Stock [Member]
Initial Public Offering of Common Stock [Abstract]
Treasury stock repurchase		$ 30,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-03-31
Revenue, Performance Obligation [Abstract]
Remaining performance obligation percentage				84.20%
Remaining performance obligation, expected timing of satisfaction, period				9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Performance Obligation [Abstract]
Remaining performance obligation percentage				10.30%
Remaining performance obligation, expected timing of satisfaction, period				1 year
Federal [Member]
Disaggregation of Revenue [Abstract]
Revenue				$ 53,347	36,092
State & Local, and Commercial [Member]
Disaggregation of Revenue [Abstract]
Revenue				$ 2,410	$ 2,888
Service Based RSU Awards [Member] | Senior Executive Officer [Member]
Share Based Compensation [Abstract]
Number of annual installments | Installment				3
Vesting percentage on first anniversary				30.00%
Vesting percentage on second anniversary				30.00%
Vesting percentage on third anniversary				40.00%
Unvested Restricted Stock and Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount | shares				3,167	957
Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount | shares				901	901