Investments in Unconsolidated Entities, Medical Oncology Partners (Details) - USD ($)		3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2021	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 23, 2016
Medical Oncology Partners [Abstract]
Investments in unconsolidated entities		$ 141,000	$ 152,000	$ 164,000	$ 161,000	$ 164,000	$ 152,000	$ 141,000	$ 160,000
Advances to unconsolidated entities								491,000	459,000
Condensed Income Statement Information [Abstract]
Patient revenue		0	0	0	1,061,000	1,061,000	1,061,000	1,061,000	3,173,000
Net loss		(296,000)	(352,000)	(617,000)	292,000	(325,000)	(677,000)	(973,000)	533,000
USNC's equity in (loss) income		(119,000)	(77,000)	(135,000)	(139,000)	(274,000)	(351,000)	(470,000)	(809,000)
Condensed Balance Sheet Information [Abstract]
Current assets		2,243,000	2,634,000	2,909,000	3,451,000	2,909,000	2,634,000	2,243,000	3,007,000
Total assets		3,688,000	3,772,000	4,073,000	4,614,000	4,073,000	3,772,000	3,688,000	4,173,000
Current liabilities		626,000	718,000	656,000	569,000	656,000	718,000	626,000	410,000
Noncurrent liabilities			45,000	56,000	67,000	56,000	45,000
Deficit		3,028,000	3,009,000	3,361,000	3,978,000	3,361,000	3,009,000	3,028,000	3,686,000	$ 3,153,000
Total liabilities and deficit		3,688,000	$ 3,772,000	$ 4,073,000	$ 4,614,000	$ 4,073,000	$ 3,772,000	$ 3,688,000	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
Investments in unconsolidated entities		0						0
Amount of capital contributed by company									125,000
Advances to unconsolidated entities								461,000
Condensed Income Statement Information [Abstract]
USNC's equity in (loss) income	$ (12,000)								(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%
Investments in unconsolidated entities		$ 149,000						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
Percentage of equity interest to an additional investor as a consulting fee for services								5.00%
Ownership percentage		76.67%						76.67%
Medical Oncology Partners LLC [Member] | Investment in Unconsolidated Entity [Member]
Condensed Income Statement Information [Abstract]
Patient revenue								$ 2,417,000	2,104,000
Net loss								(646,000)	(1,256,000)
USNC's equity in (loss) income								(231,000)	(450,000)
Condensed Balance Sheet Information [Abstract]
Current assets		$ 201,000						201,000	204,000
Noncurrent assets		384,000						384,000	701,000
Total assets		585,000						585,000	905,000
Current liabilities		3,109,000						3,109,000	2,736,000
Noncurrent liabilities		92,000						92,000	410,000
Deficit		(2,616,000)						(2,616,000)	(2,241,000)
Total liabilities and deficit		$ 585,000						$ 585,000	$ 905,000