Summary of Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2020		Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Revenue	$ 44,887		$ 47,440		$ 48,610		$ 38,980		$ 46,473		$ 45,531		$ 36,048		$ 31,166		$ 179,917	$ 159,218	$ 138,016
Gross profit	16,043		16,562		17,573		12,242		17,040		16,313		10,015		8,976
Loss before income taxes and non-controlling interest	2,825		2,502		3,074		(1,606)		(838)		3,708		(1,974)		(3,137)		6,795	(2,241)	1,768
Net (loss) income attributable to Telos Corporation (1)(2)	$ 3,865	[1]	$ (200)	[1]	$ 266	[1],[2]	$ (2,244)	[1]	$ (3,480)	[1]	$ 2,233	[1],[3]	$ (1,741)	[1]	$ (3,413)	[1]	$ 1,687	$ (6,401)	$ (1,640)
Weighted-average common shares outstanding, basic (in shares)	50,383		39,002		38,583		38,073		38,073		38,073		37,642		37,116		41,642,000	37,729,000	36,762,000
Weighted-average common shares outstanding, diluted (in shares)	51,288		39,002		39,927		38,073		38,073		39,931		37,642		37,116		42,877,000	37,729,000	36,762,000
Basic net (loss) earnings per share (in dollars per share)	$ 0.08		$ (0.01)		$ 0.01		$ (0.06)		$ (0.09)		$ 0.06		$ (0.05)		$ (0.09)		$ 0.04	$ (0.17)	$ (0.04)
Diluted net (loss) earnings per share (in dollars per share)	$ 0.08		$ (0.01)		$ 0.01		$ (0.06)		$ (0.09)		$ 0.06		$ (0.05)		$ (0.09)		$ 0.04	$ (0.17)	$ (0.04)
Software Sales [Member]
Quarterly Financial Data [Abstract]
Revenue											$ 2,600

[1] Changes in net income are the result of several factors, including seasonality of the government year-end buying season, as well as the nature and timing of other deliverables.

[2] Net income for the second quarter of 2020 is attributable to a change in the mix and timing of Telos ID deliverables.

[3] Net income for the third quarter of 2019 is attributable to $2.6 million in proprietary software sales which carry lower cost of sales.