Investment in Unconsolidated Entities (Details)		12 Months Ended
	Feb. 28, 2014 USD ($)	Dec. 31, 2015 USD ($) ft² Member	Dec. 31, 2014 USD ($)	Jan. 31, 2013 USD ($)	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011 USD ($)	Sep. 30, 2010 USD ($)
The Southern California Regional Gamma Knife Center [Abstract]
Renovation installation and operation agreement period		14 years
Condensed Income Statement Information [Abstract]
Revenue		$ 2,971,000	$ 2,607,000
USNC's equity in (loss) income of investment in unconsolidated entities		285,000	14,000
Florida Oncology Partners [Abstract]
Recorded investments		364,000	323,000
Due from related parties		21,000	8,000
Boca Oncology Partners [Abstract]
Investment in unconsolidated entities		364,000	323,000
Proceeds from short-term loans		$ 0	462,000
Boca Oncology Partners, LLC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage		11.25%
Condensed Income Statement Information [Abstract]
Revenue			115,000
Net (loss) income			(108,000)
USNC's equity in (loss) income of investment in unconsolidated entities			(12,000)
Boca Oncology Partners [Abstract]
Area of real estate property | ft²		6,000
Gain from sale of interests	$ 204,000
Amount loaned to related parties		$ 56,250
Debt maturity period		5 years
Company loan interest rate		7.00%
Number of members who provided short term loans | Member		3
Proceeds from short-term loans	$ 462,000
Accrued interest		$ 26,000
Boca Oncology Partners, LLC [Member] | USNC [Member]
Boca Oncology Partners [Abstract]
Amount loaned to related parties		$ 28,000
Boca Oncology Partners RE, LLC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage		15.40%
Condensed Income Statement Information [Abstract]
Rental income		$ 3,000	0
Net (loss) income		3,000	(4,000)
USNC's equity in (loss) income of investment in unconsolidated entities		0	0
Condensed Balance Sheet Information [Abstract]
Current assets		40,000	61,000
Noncurrent assets		837,000	786,000
Total assets		877,000	847,000
Current liabilities		0	0
Noncurrent liabilities		0	0
Equity		877,000	847,000
Total liabilities and equity		877,000	847,000
Florida Oncology Partners [Abstract]
Recorded investments		$ 139,000	134,000
Ownership percentage by outside investors		31.50%
Boca Oncology Partners [Abstract]
Percentage of interest in medical office building		20.00%
Investment in unconsolidated entities		$ 139,000	134,000
BOP and BOPRE [Member]
Florida Oncology Partners [Abstract]
Ownership percentage by outside investors		88.75%
Boca Oncology Partners [Abstract]
Area of real estate property | ft²		32,000
Additional investor purchased		50.00%
BOP and BOPRE [Member] | USNC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage							22.50%
Florida Oncology Partners [Abstract]
Recorded investments							$ 225,000
Boca Oncology Partners [Abstract]
Investment in unconsolidated entities							$ 225,000
Boca West IMP [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage		23.75%				3.75%
BOP and USNC's [Member]
Boca Oncology Partners [Abstract]
Reduced ownership percentage		15.40%
CGK [Member] | USNC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage					39.00%		44.00%
Initial ownership percentage		27.00%
Neuro Partners LLC [Member] | USNC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage		20.00%
FOP and FOPRE [Member]
Condensed Income Statement Information [Abstract]
Revenue		$ 3,157,000	2,631,000
Net (loss) income		1,344,000	197,000
USNC's equity in (loss) income of investment in unconsolidated entities		323,000	39,000
Condensed Balance Sheet Information [Abstract]
Current assets		1,024,000	606,000
Noncurrent assets		3,066,000	5,070,000
Total assets		4,090,000	5,676,000
Current liabilities		1,848,000	858,000
Noncurrent liabilities		1,529,000	3,947,000
Equity		713,000	871,000
Total liabilities and equity		4,090,000	5,676,000
Florida Oncology Partners [Abstract]
Recorded investments		$ 225,000	190,000
Ownership percentage by outside investors		76.00%
Due from related parties		$ 21,000	8,000
Gain on sale of building		577,000
Boca Oncology Partners [Abstract]
Investment in unconsolidated entities		$ 225,000	190,000
FOP and FOPRE [Member] | USNC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage		24.00%						20.00%
Florida Oncology Partners [Abstract]
Recorded investments								$ 200,000
Boca Oncology Partners [Abstract]
Investment in unconsolidated entities								$ 200,000
Neuro Partners LLC and CGK [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Losses against outstanding receivables		$ 62,000	45,000
Condensed Income Statement Information [Abstract]
Revenue		912,000	1,223,000
Net (loss) income		(184,000)	74,000
USNC's equity in (loss) income of investment in unconsolidated entities		(84,000)	14,000
Condensed Balance Sheet Information [Abstract]
Current assets		66,000	92,000
Noncurrent assets		394,000	991,000
Total assets		460,000	1,083,000
Current liabilities		1,359,000	829,000
Noncurrent liabilities		0	969,000
Equity		(899,000)	(715,000)
Total liabilities and equity		460,000	1,083,000
Boca Oncology Partners [Abstract]
Losses against outstanding receivables		$ 62,000	45,000
Broward Oncology Partners, LLC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage				12.50%
Condensed Income Statement Information [Abstract]
Revenue			505,000
Net (loss) income			255,000
USNC's equity in (loss) income of investment in unconsolidated entities			$ 32,000
Florida Oncology Partners [Abstract]
Recorded investments				$ 50,000
Boca Oncology Partners [Abstract]
Investment in unconsolidated entities				$ 50,000