Investments in Unconsolidated Entities, CB Oncology Partners (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Sep. 02, 2017
CB Oncology Partners [Abstract]
Interest earned from the amounts owed by entity		$ 0	$ 3,000
Condensed Income Statement Information [Abstract]
Patient revenue		1,061,000	3,173,000
Net loss		(674,000)	533,000
USNC's equity in (loss) income		(470,000)	(809,000)
Condensed Balance Sheet Information [Abstract]
Current assets		2,243,000	3,007,000
Total assets		3,688,000	4,173,000
Current liabilities		327,000	410,000
Deficit		3,327,000	3,686,000	$ 3,153,000
Total liabilities and deficit		3,688,000	4,173,000
CB Oncology Partners LLC Member [Member]
CB Oncology Partners [Abstract]
Ownership percentage	28.58%				24.00%
Capital called from members	$ 500,000
Advances converted into equity	121,000
Contribution in cash	$ 212,000
Outstanding amount		2,174,000	2,154,000
Allowances on outstanding amount		1,251,000	1,251,000
Due from related parties		$ 923,000	$ 903,000
Note bearing interest		6.00%	6.00%
Interest earned from the amounts owed by entity		$ 125,000	$ 125,000
Accrued interest		398,000	273,000
CB Oncology Partners LLC Member [Member] | Investment in Unconsolidated Entity [Member]
Condensed Income Statement Information [Abstract]
Patient revenue		2,042,000	1,795,000
Net loss		(319,000)	(730,000)
USNC's equity in (loss) income		(91,000)	(195,000)
Condensed Balance Sheet Information [Abstract]
Current assets		400,000	385,000
Noncurrent assets		3,667,000	4,271,000
Total assets		4,067,000	4,656,000
Current liabilities		3,472,000	3,181,000
Noncurrent liabilities		3,121,000	3,684,000
Deficit		(2,526,000)	(2,209,000)
Total liabilities and deficit		$ 4,067,000	$ 4,656,000