Investments in Unconsolidated Entities, Medical Oncology Partners (Details) - USD ($)			12 Months Ended
	Dec. 31, 2022	Dec. 31, 2016	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 23, 2016
Medical Oncology Partners [Abstract]
Investments in unconsolidated entities	$ 157,000		$ 157,000	$ 141,000
Condensed Income Statement Information [Abstract]
Patient revenue			0	1,061,000
Net (loss) income			(1,572,000)	(973,000)
USNC's equity in (loss) income			16,000	(19,000)
Condensed Balance Sheet Information [Abstract]
Current assets	1,555,000		1,555,000	2,243,000
Total assets	1,747,000		1,747,000	3,688,000
Current liabilities	280,000		280,000	626,000
Deficit	1,456,000		1,456,000	3,028,000	$ 3,686,000
Total liabilities and deficit	1,747,000		1,747,000	3,688,000
USNC [Member]
Medical Oncology Partners [Abstract]
Proceeds from sale of assets	2,060,000		2,060,000
Payment for management fees	1,300,000		1,300,000
Medical Oncology Partners LLC [Member]
Condensed Income Statement Information [Abstract]
Patient revenue			0	2,417,000
Net (loss) income			1,547,000	(646,000)
Condensed Balance Sheet Information [Abstract]
Current assets	0		0	201,000
Noncurrent assets	0		0	384,000
Total assets	0		0	585,000
Current liabilities	1,075,000		1,075,000	3,109,000
Noncurrent liabilities	0		0	92,000
Deficit	(1,075,000)		(1,075,000)	(2,616,000)
Total liabilities and deficit	0		$ 0	585,000
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
Condensed Income Statement Information [Abstract]
USNC's equity in (loss) income		$ (12,000)	0	$ (231,000)
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%