Basis of Presentation - Narrative (Details)					3 Months Ended		9 Months Ended
	Jun. 10, 2020 USD ($) shares	May 26, 2020 $ / shares shares	Sep. 10, 2019 USD ($) $ / shares shares	Sep. 09, 2019 USD ($) $ / shares	Sep. 30, 2020 USD ($) $ / shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) $ / shares	Sep. 30, 2019 USD ($)	Sep. 17, 2020 $ / shares shares	Apr. 30, 2020 $ / shares	Apr. 01, 2020	Dec. 31, 2019 USD ($) $ / shares
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction in executive salaries											20.00%
Reduction in salaried employee salaries											20.00%
Reduction of working hours for hourly employees											20.00%
Workforce brought back					20.00%		20.00%
Series A Cumulative Perpetual Preferred Stock, dividend rate			0.100				0.100
Series A Cumulative Perpetual Preferred Stock, par value (USD per share)			$ 0.0001
Preferred stock, dividend rate percentage							10.00%
Preferred stock, par value (in usd per share) | $ / shares					$ 0.0001		$ 0.0001
Preferred stock, liquidation preference per share (USD per share) | $ / shares					10.00		10.00
Common stock, par value (in usd per share) | $ / shares					0.0001		0.0001					$ 0.0001
Gross proceeds from private placement				$ 3,000,000.0
Shares reserved for future issuance (in shares) | shares									1,492,321
Exercise price of warrants (usd per share) | $ / shares					$ 2.25		$ 2.25
Net proceeds from sale of common stock and warrants							$ 4,203,000	$ 0
Payments issuance costs							3,000	150,000
Proceeds from exercise of over-allotment options and warrants							892,000	0
(Loss) income from operations by segment					$ (1,533,000)	$ (1,209,000)	(5,663,000)	(3,490,000)
Accumulated deficit					(124,529,000)		(124,529,000)					$ (118,529,000)
Net cash provided by (used in) operating activities							(1,880,000)	$ (765,000)
Short-term debt and current portion of long-term debt					4,260,000		4,260,000					4,036,000
Payable to related parties					2,155,000		2,155,000					1,920,000
Derivative liability												$ 10,000
Capitalized implementation costs							700,000
Private Placement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of shares issued in transaction (in shares) | shares			300,000
Price of stock sold (in dollars per share) | $ / shares			$ 10.00	$ 10.00
Gross proceeds from private placement			$ 3,000,000.0
Equity Offering
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Common stock, par value (in usd per share) | $ / shares										$ 0.0001
Number of shares issued in transaction (in shares) | shares	2,450,000	2,225,000
Price of stock sold (in dollars per share) | $ / shares		$ 2.25
Gross proceeds from private placement	$ 5,500,000
Number of securities called by warrants (in shares) | shares		1,112,500
Net proceeds from sale of common stock and warrants							4,200,000
Payments issuance costs							800,000
Proceeds from exercise of over-allotment options and warrants							900,000
Proceeds from issuance of common stock to fund modular housing project							3,000,000.0
Equity Offering | Common stock
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Price of stock sold (in dollars per share) | $ / shares		$ 2.24
Equity Offering | Stock warrants
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Price of stock sold (in dollars per share) | $ / shares		$ 0.01
Number of warrants issued in transaction (in shares) | shares		2,225,000
Over-Allotment Option
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Price of stock sold (in dollars per share) | $ / shares		$ 2.24
Number of securities called by warrants (in shares) | shares		225,000
Exercise price of warrants (usd per share) | $ / shares		$ 0.01
Over-Allotment Option | Stock warrants
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of warrants issued in transaction (in shares) | shares		225,000
Number of securities called by warrants (in shares) | shares		112,500
Healthcare
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in revenue					(3,800,000)		(12,900,000)
Building and Construction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in revenue					5,800,000		16,300,000
ATRM Holdings, Inc.
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shares issued in business acquisition (In shares) | shares			1,615,637
Series A Preferred Stock
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Digirad shares issued per ATRM share (in shares)				0.03
Preferred stock, par value (in usd per share) | $ / shares									$ 0.0001
Shares reserved for future issuance (in shares) | shares									1,492,321
Series A Preferred Stock | Put Option
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Derivative liability					$ 1,000,000.0		$ 1,000,000.0
Series A Preferred Stock | ATRM Holdings, Inc.
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Digirad shares issued per ATRM share (in shares)			0.03
Shares issued in business acquisition (In shares) | shares			1,615,637
Series B Preferred Stock | ATRM Holdings, Inc.
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Digirad shares issued per ATRM share (in shares)			2.5	2.5
ATRM Holdings, Inc.
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Preferred stock, dividend rate percentage			10.00%
Preferred stock, par value (in usd per share) | $ / shares			$ 0.001