Per Share Amounts (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income attributable to American Shared Hospital Services	$ 113,000	$ 93,000	$ 406,000	$ 144,000
Weighted average common shares for basic earnings per share	5,935,000	5,552,000	5,725,000	5,548,000
Diluted effect of stock options and restricted stock	208,000	16,000	196,000	16,000
Weighted average common shares for diluted earnings per share	6,143,000	5,568,000	5,921,000	5,564,000
Basic earnings per share	$ 0.02	$ 0.02	$ 0.07	$ 0.03
Diluted earnings per share	$ 0.02	$ 0.02	$ 0.07	$ 0.03