The Southern California Regional Gamma Knife Center (Details)		1 Months Ended	3 Months Ended
	Apr. 01, 2016 USD ($)	Feb. 29, 2016 USD ($)	Mar. 31, 2019 USD ($) Payment	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
The Southern California Regional Gamma Knife Center [Abstract]
Renovation installation and operation agreement period			14 years
Due from related parties			$ 1,246,000		$ 1,141,000
Condensed Income Statement Information [Abstract]
Patient revenue			841,000	$ 865,000
USNC's equity in earnings			(233,000)	(30,000)
Neuro Partners LLC and CGK [Member]
The Southern California Regional Gamma Knife Center [Abstract]
USNC's equity in earnings not recorded due to prior losses incurred				13,000
Recorded amount of equity method income			43,000	0
Condensed Income Statement Information [Abstract]
Patient revenue			300,000	211,000
Net income			125,000	57,000
USNC's equity in earnings			43,000	$ 13,000
Condensed Balance Sheet Information [Abstract]
Current assets			406,000		304,000
Noncurrent assets			1,000,000		1,064,000
Total assets			1,406,000		1,368,000
Current liabilities			405,000		399,000
Noncurrent liabilities			832,000		924,000
Equity			169,000		45,000
Total liabilities and equity (deficit)			$ 1,406,000		$ 1,368,000
Neuro Partners LLC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage			20.00%
Neuro Partners LLC [Member] | Lease One [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Share of guarantee in lease obligations			20.00%
Lease term			7 years
Neuro Partners LLC [Member] | Lease Two [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Lease term			5 years
Number of lease payments | Payment			60
Capital lease obligation		$ 1,663,000
Prior year lease obligations		$ 668,000
Capital lease payment	$ 31,000
CGK [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage			39.00%
Due from related parties			$ 20,000
Other receivables			$ 3,000