Investment in Unconsolidated Entities (Details) (USD $)	12 Months Ended		0 Months Ended
	Dec. 31, 2014 Member	Dec. 31, 2013	May 31, 2014	Feb. 28, 2014	Dec. 31, 2011	Jun. 30, 2012	Dec. 31, 2012	Sep. 30, 2010	Jan. 31, 2013
The Southern California Regional Gamma Knife Center [Abstract]
Renovation installation and operation agreement period	14 years
Condensed Income Statement Information [Abstract]
Patient revenue	$ 2,607,000	$ 0
USNC's equity in income (loss) of investment in unconsolidated entities	14,000	(31,000)
Florida Oncology Partners [Abstract]
Recorded investments	323,000	320,000
Due from related parties	8,000	316,000
Boca Oncology Partners [Abstract]
Investment in unconsolidated entities	323,000	320,000
Number of members who provided short term loans	3
Proceeds from short-term loans	462,000	0
Interest expense	184,000	15,000
Accrued interest	15,000
USNC [Member]
Boca Oncology Partners [Abstract]
Reduced ownership percentage (in hundredths)	11.25%
Boca Oncology Partners, LLC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Losses against outstanding receivables		57,000
Condensed Income Statement Information [Abstract]
Patient revenue	115,000	2,386,000
Net income (loss)	(108,000)	(206,000)
USNC's equity in income (loss) of investment in unconsolidated entities	(12,000)	(23,000)
Condensed Balance Sheet Information [Abstract]
Current assets		640,000
Noncurrent assets		1,831,000
Total assets		2,471,000
Current liabilities		730,000
Noncurrent liabilities		2,126,000
Equity		(385,000)
Total liabilities and equity		2,471,000
Boca Oncology Partners [Abstract]
Area of real estate property	6,000
Gain from sale of interests			33,000	204,000
Amount loaned to related parties	56,250
Debt maturity period	5 years
Company loan interest rate (in hundredths)	7.00%
Losses against outstanding receivables		57,000
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 (in hundredths)	15.40%				22.50%
Condensed Income Statement Information [Abstract]
Rental income	0	0
Net income (loss)	(4,000)	(1,000)
USNC's equity in income (loss) of investment in unconsolidated entities	0	0
Condensed Balance Sheet Information [Abstract]
Current assets	61,000	132,000
Noncurrent assets	786,000	707,000
Total assets	847,000	839,000
Current liabilities	0	0
Noncurrent liabilities	0	0
Equity	847,000	839,000
Total liabilities and equity	847,000	839,000
Florida Oncology Partners [Abstract]
Recorded investments	134,000	0
Ownership percentage by outside investors (in hundredths)	31.50%
Boca Oncology Partners [Abstract]
Percentage of interest in medical office building (in hundredths)	20.00%
Investment in unconsolidated entities	134,000	0
Due to related parties	12,000	0
Boca Oncology Partners RE, LLC [Member] | USNC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage (in hundredths)	11.25%
BOP and BOPRE [Member]
Florida Oncology Partners [Abstract]
Recorded investments					225,000
Ownership percentage by outside investors (in hundredths)	88.75%
Due from related parties	0	200,000
Boca Oncology Partners [Abstract]
Area of real estate property	32,000
Investment in unconsolidated entities					225,000
Additional investor purchased (in hundredths)	50.00%
Boca West IMP [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage (in hundredths)	3.75%					23.75%
BOP and USNC's [Member] | USNC [Member]
Boca Oncology Partners [Abstract]
Reduced ownership percentage (in hundredths)	15.40%
CGK [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage (in hundredths)					44.00%		39.00%
CGK [Member] | USNC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Initial ownership percentage (in hundredths)	27.00%
Neuro Partners LLC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage (in hundredths)	20.00%
FOP and FOPRE [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage (in hundredths)	20.00%
Condensed Income Statement Information [Abstract]
Patient revenue	2,631,000	2,836,000
Net income (loss)	197,000	281,000
USNC's equity in income (loss) of investment in unconsolidated entities	39,000	56,000
Condensed Balance Sheet Information [Abstract]
Current assets	606,000	653,000
Noncurrent assets	5,070,000	5,795,000
Total assets	5,676,000	6,448,000
Current liabilities	858,000	893,000
Noncurrent liabilities	3,947,000	4,881,000
Equity	871,000	674,000
Total liabilities and equity	5,676,000	6,448,000
Florida Oncology Partners [Abstract]
Recorded investments	190,000	151,000						200,000
Ownership percentage by outside investors (in hundredths)	80.00%
Due from related parties	8,000	40,000
Boca Oncology Partners [Abstract]
Investment in unconsolidated entities	190,000	151,000						200,000
Neuro Partners LLC and CGK [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Losses against outstanding receivables	45,000	27,000
Condensed Income Statement Information [Abstract]
Patient revenue	1,223,000	1,040,000
Net income (loss)	74,000	(180,000)
USNC's equity in income (loss) of investment in unconsolidated entities	14,000	(75,000)
Condensed Balance Sheet Information [Abstract]
Current assets	92,000	521,000
Noncurrent assets	991,000	1,626,000
Total assets	1,083,000	2,147,000
Current liabilities	829,000	1,272,000
Noncurrent liabilities	969,000	1,664,000
Equity	(715,000)	(789,000)
Total liabilities and equity	1,083,000	2,147,000
Boca Oncology Partners [Abstract]
Losses against outstanding receivables	45,000	27,000
Broward Oncology Partners, LLC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage (in hundredths)									12.50%
Condensed Income Statement Information [Abstract]
Patient revenue	505,000	522,000
Net income (loss)	255,000	(120,000)
USNC's equity in income (loss) of investment in unconsolidated entities	32,000	(15,000)
Condensed Balance Sheet Information [Abstract]
Current assets		360,000
Noncurrent assets		239,000
Total assets		599,000
Current liabilities		319,000
Equity		280,000
Total liabilities and equity		599,000
Florida Oncology Partners [Abstract]
Recorded investments									50,000
Boca Oncology Partners [Abstract]
Investment in unconsolidated entities									50,000
Interest expense				$ 26,000