Note 6 - Per Share Amounts - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Net income (loss) attributable to American Shared Hospital Services	$ 497,000	$ (87,000)	$ 766,000	$ (58,000)
Weighted average common shares for basic earnings (loss) per share (in shares)	6,203,000	5,802,000	6,187,000	5,801,000
Diluted effect of stock options and restricted stock awards (in shares)	78,000	0	79,000	0
Weighted average common shares for diluted earnings (loss) per share (in shares)	6,281,000	5,802,000	6,266,000	5,801,000
Basic earnings (loss) per share (in dollars per share)	$ 0.08	$ (0.01)	$ 0.12	$ (0.01)
Diluted earnings (loss) per share (in dollars per share)	$ 0.08	$ (0.01)	$ 0.12	$ (0.01)