Note 3 - Earnings Per Share - Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income attributable to SPAR Group, Inc.	$ 1,144	$ 907	$ 1,337	$ 3,045
Shares used in basic net income per share calculation (in shares)	21,110	20,975	21,108	20,856
Stock options and unvested restricted shares (in shares)	37	86	44	240
Shares used in diluted net income per share calculations (in shares)	21,147	21,061	21,152	21,096
Basic and diluted net income per common share: (in dollars per share)	$ 0.05	$ 0.04	$ 0.06	$ 0.15