Investments in Unconsolidated Entities, Florida Oncology Partners (Details)	1 Months Ended	3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($) shares	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($) Term	Dec. 31, 2020 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2011 USD ($)	Nov. 30, 2017 USD ($)	Sep. 22, 2017 USD ($)
Florida Oncology Partners [Abstract]
Down payment of capital leases								$ 89,000	$ 901,000
Recorded distribution								0	176,000
Investments in unconsolidated entities		$ 141,000	$ 152,000	$ 164,000	$ 161,000	$ 164,000	$ 152,000	141,000	160,000
USNC's equity in (loss) income		$ (119,000)	$ (77,000)	$ (135,000)	$ (139,000)	$ (274,000)	$ (351,000)	$ (470,000)	(809,000)
FOP [Member]
Florida Oncology Partners [Abstract]
Lease term		7 years						7 years
Lease obligation											$ 5,800,000
Percentage of guarantee obligations											25.00%
Down payment of capital leases										$ 1,000,000
Monthly payments for capital leases										$ 172,000
Common stock awarded as a part of bankruptcy proceedings (in shares) | shares	10,820
Recorded distribution								$ 0	0
Received from related party									155,000
Investments in unconsolidated entities		$ 0						$ 0	0
USNC's equity in (loss) income									(78,000)
FOP [Member] | Maximum [Member]
Florida Oncology Partners [Abstract]
Amount of guarantee obligation											$ 1,433,000
FOP [Member] | Office Space [Member]
Florida Oncology Partners [Abstract]
Lease term		10 years						10 years
Loan amount												$ 4,106,000
Debt maturity period								7 years
FOP [Member] | Radiation Therapy Center [Member]
Florida Oncology Partners [Abstract]
Lease term		10 years						10 years
Lease obligation													$ 14,321,000
Monthly payments for capital leases	$ 160,000	$ 170,000						$ 170,000
Maximum number of additional terms extended | Term								3
Extension of agreement								5 years
Percentage of increase of monthly payments each year								2.00%
FOP [Member] | Letter of Credit [Member] | Office Space [Member]
Florida Oncology Partners [Abstract]
Letter of credit, amount		$ 88,000						$ 88,000
FOP [Member] | USNC [Member]
Florida Oncology Partners [Abstract]
Ownership percentage		24.00%						24.00%
21st Century Oncology [Member]
Florida Oncology Partners [Abstract]
Recorded distribution									$ 158,000