Per Share Amounts - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income attributable to American Shared Hospital Services	$ 165	$ 168	$ 466	$ 845
Weighted average common shares for basic earnings per share (in shares)	5,889	5,841	5,899	5,831
Diluted effect of stock options and restricted stock (in shares)	19	50	18	24
Weighted average common shares for diluted earnings per share (in shares)	5,908	5,891	5,917	5,855
Basic earnings per share (in USD per share)	$ 0.03	$ 0.03	$ 0.08	$ 0.14
Diluted earnings per share (in USD per share)	$ 0.03	$ 0.03	$ 0.08	$ 0.14