Boca Oncology Partners (Details)	1 Months Ended		3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011 USD ($)	Mar. 31, 2022 USD ($) ft²	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2021 USD ($)
Boca Oncology Partners [Abstract]
Recorded investments			$ 146,000			$ 141,000
Condensed Income Statement Information [Abstract]
Net income			(495,000)	$ 292,000	$ 292,000
USNC's equity in earnings (loss)			(133,000)	(139,000)
Condensed Balance Sheet Information [Abstract]
Current assets			1,705,000			2,243,000
TOTAL ASSETS			3,180,000			3,688,000
Current liabilities			624,000			327,000
Equity			2,533,000			3,327,000
TOTAL LIABILITIES AND EQUITY			3,180,000			3,688,000
Boca Oncology Partners RE, LLC ("BOPRE") [Member]
Condensed Income Statement Information [Abstract]
Rental income			0	0
Net income			17,000	18,000
Condensed Balance Sheet Information [Abstract]
Current assets			80,000			112,000
Noncurrent assets			757,000			757,000
TOTAL ASSETS			837,000			869,000
Current liabilities			0			0
Noncurrent liabilities			0			0
Equity			837,000			869,000
TOTAL LIABILITIES AND EQUITY			$ 837,000			$ 869,000
Boca Oncology Partners, LLC [Member]
Boca Oncology Partners [Abstract]
Area of real estate property (in square foot) | ft²			6,000
Boca Oncology Partners RE, LLC ("BOPRE") [Member]
Boca Oncology Partners [Abstract]
Ownership percentage			24.36%			24.36%
Recorded investments			$ 145,000			$ 151,000
Condensed Income Statement Information [Abstract]
USNC's equity in earnings (loss)			$ 4,000	$ 3,000
Boca Oncology Partners RE, LLC ("BOPRE") [Member] | Boca West IMP [Member]
Boca Oncology Partners [Abstract]
Percentage of interest in medical office building		20.00%
Ownership percentage	23.75%
Additional investor purchased ownership percentage	3.75%
BOP and BOPRE [Member]
Boca Oncology Partners [Abstract]
Area of real estate property (in square foot) | ft²			32,000
Investments in unconsolidated entities		$ 225,000
Ownership percentage		22.50%