Medical Oncology Partners (Details) - USD ($)		3 Months Ended		12 Months Ended
	Dec. 31, 2016	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 23, 2016
Medical Oncology Partners [Abstract]
Carrying value of investment		$ 161,000		$ 160,000
Advances to unconsolidated entities		144,000	$ 172,000
Condensed Consolidated Income Statement Information [Abstract]
Patient revenue		1,061,000	747,000
USNC's equity in income (loss)		(139,000)	(146,000)
Condensed Consolidated Balance Sheet Information [Abstract]
Current assets		3,451,000		3,007,000
TOTAL ASSETS		4,614,000		4,173,000
Current liabilities		322,000		410,000
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY		$ 4,614,000		4,173,000
Medical Oncology Partners LLC [Member]
Medical Oncology Partners [Abstract]
Equity interest percentage to be acquired by subsidiary		100.00%
Investments in unconsolidated entities		$ 450,000
Amount of capital contributed by company			36,000
Advances to unconsolidated entities		141,000
Condensed Consolidated Income Statement Information [Abstract]
USNC's equity in income (loss)	$ (12,000)	(140,000)		(686,000)
Medical Oncology Partners LLC [Member] | Other Investor [Member]
Medical Oncology Partners [Abstract]
Investments in unconsolidated entities		105,000
Medical Oncology Partners LLC [Member] | USNC [Member]
Medical Oncology Partners [Abstract]
Investments in unconsolidated entities		173,000
Ownership percentage					35.83%
Carrying value of investment		149,000			$ 161,000
Medical Oncology Partners LLC [Member] | USNC [Member] | Dr. Jaime Lozano [Member]
Medical Oncology Partners [Abstract]
Investments in unconsolidated entities		$ 345,000
Ownership percentage		76.67%
Percentage of equity interest to an additional investor as a consulting fee for services		5.00%
Medical Oncology Partners LLC [Member] | Investment in Unconsolidated Entity [Member]
Condensed Consolidated Income Statement Information [Abstract]
Patient revenue		$ 537,000	515,000
Net loss		(168,000)	(234,000)
USNC's equity in income (loss)		(60,000)	$ (84,000)
Condensed Consolidated Balance Sheet Information [Abstract]
Current assets		202,000		204,000
Noncurrent assets		624,000		701,000
TOTAL ASSETS		826,000		905,000
Current liabilities		2,961,000		2,736,000
Noncurrent liabilities		278,000		410,000
Deficit		(2,413,000)		(2,241,000)
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY		$ 826,000		$ 905,000