Note 6 - Per Share Amounts - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Net income (loss) attributable to American Shared Hospital Services	$ 316,000	$ 33,000	$ 1,082,000	$ (25,000)
Weighted average common shares for basic earnings (loss) per share (in shares)	6,234,000	6,103,000	6,223,000	5,824,000
Dilutive effect of stock options and restricted stock awards (in shares)	39,000	20,000	38,000	0
Weighted average common shares for diluted earnings (loss) per share (in shares)	6,273,000	6,123,000	6,261,000	5,824,000
Basic earnings (loss) per share (in dollars per share)	$ 0.05	$ 0.01	$ 0.17	$ (0.00)
Diluted earnings (loss) per share (in dollars per share)	$ 0.05	$ 0.01	$ 0.17	$ (0.00)