Note 9 - Segment Information - Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Net revenues	$ 50,944		$ 68,223		$ 112,292	$ 125,383
Operating income (loss)	1,963		4,230		3,440	5,961
Interest expense	84		187		312	388
Other income, net	(50)		(192)		(58)	(257)
Income before income tax expense	1,929		4,235		3,186	5,830
Income tax expense	624		1,428		959	1,986
Net income	1,305	$ 922	2,807	$ 1,037	2,227	3,844
Net income (loss) attributable to non-controlling interest	(1,408)		(1,284)		(2,034)	(1,705)
Total net income attributable to SPAR Group, Inc.	(103)		1,523		193	2,139
Depreciation and amortization	539		528		1,079	1,038
Capital expenditures	444		471		786	935
US Segment [Member]
Net revenues	22,123		28,006		45,412	46,662
Operating income (loss)	315		2,608		623	3,360
Interest expense	144		185		276	246
Other income, net	(1)		(1)		(1)	(1)
Income before income tax expense	172		2,424		348	3,115
Income tax expense	124		501		199	702
Net income	48		1,923		149	2,413
Net income (loss) attributable to non-controlling interest	(519)		(679)		(583)	(775)
Total net income attributable to SPAR Group, Inc.	(471)		1,244		(434)	1,638
Depreciation and amortization	419		382		832	754
Capital expenditures	288		344		669	722
International Segment [Member]
Net revenues	28,821		40,217		66,880	78,721
Operating income (loss)	1,648		1,622		2,817	2,601
Interest expense	(60)		2		36	142
Other income, net	(49)		(191)		(57)	(256)
Income before income tax expense	1,757		1,811		2,838	2,715
Income tax expense	500		927		760	1,284
Net income	1,257		884		2,078	1,431
Net income (loss) attributable to non-controlling interest	(889)		(605)		(1,451)	(930)
Total net income attributable to SPAR Group, Inc.	368		279		627	501
Depreciation and amortization	120		146		247	284
Capital expenditures	$ 156		$ 127		$ 117	$ 213