The Southern California Regional Gamma Knife Center (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Renovation installation and operation agreement period			14 years
Neuro Partners LLC and CGK Condensed Income Statement Information [Abstract]
Patient revenue	$ 737,000	$ 0	$ 737,000	$ 0
USNC's equity in loss of Neuro Partners, LLC and CGK	27,000	19,000	(12,000)	12,000
CGK [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	39.00%		39.00%
Neuro Partners LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	20.00%		20.00%
Neuro Partners LLC and CGK [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of guarantee obligations (in hundredths)			20.00%
Period of lease with respect to gamma knife equipment and certain leasehold improvements			7 years
Outstanding balance on the lease obligations	1,987,000		1,987,000
Option to purchase the gamma knife	490,000		490,000
Losses against outstanding receivables			42,000
Losses against aggregate outstanding receivables for the current period	18,000
Losses against aggregate outstanding receivables for the prior period	24,000
Neuro Partners LLC and CGK Condensed Income Statement Information [Abstract]
Patient revenue	298,000	245,000	562,000	603,000
Net loss	(1,000)	(66,000)	(25,000)	(3,000)
USNC's equity in loss of Neuro Partners, LLC and CGK	(4,000)	(28,000)	(18,000)	(6,000)
Equity Method Investment Summarized Financial Information Balance Sheet [Abstract]
Current assets	670,000		670,000		521,000
Noncurrent assets	1,308,000		1,308,000		1,626,000
Total assets	1,978,000		1,978,000		2,147,000
Current liabilities	1,477,000		1,477,000		1,272,000
Noncurrent liabilities	1,315,000		1,315,000		1,664,000
Equity	(814,000)		(814,000)		(789,000)
Total liabilities and equity	$ 1,978,000		$ 1,978,000		$ 2,147,000