Note 9 - Segment Information - Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Net revenues	$ 68,223		$ 59,224		$ 125,383	$ 113,803
Operating income (loss)	4,230		(1,237)		5,961	(506)
Interest expense	187		354		388	553
Other income, net	(192)		(232)		(257)	(304)
Income before income tax expense	4,235		(1,359)		5,830	(755)
Income tax expense	1,428		(262)		1,986	(84)
Net income (loss)	2,807	$ 1,037	(1,097)	$ 425	3,844	(671)
Net income (loss) attributable to non-controlling interest	(1,284)		(666)		(1,705)	(967)
Net income (loss) attributable to SPAR Group, Inc.	1,523		(1,763)		2,139	(1,638)
Depreciation and amortization	528		531		1,038	1,072
Capital expenditures	471		463		935	951
US Segment [Member]
Net revenues	28,006		21,556		46,662	39,925
Operating income (loss)	2,608		(1,900)		3,360	(2,219)
Interest expense	185		48		246	62
Other income, net	(1)		(29)		(1)
Income before income tax expense	2,424		(1,919)		3,115	(2,281)
Income tax expense	501		(434)		702	(446)
Net income (loss)	1,923		(1,485)		2,413	(1,835)
Net income (loss) attributable to non-controlling interest	(679)		(246)		(775)	(158)
Net income (loss) attributable to SPAR Group, Inc.	1,244		(1,730)		1,638	(1,992)
Depreciation and amortization	382		339		754	720
Capital expenditures	344		423		722	907
International Segment [Member]
Net revenues	40,217		37,668		78,721	73,878
Operating income (loss)	1,622		663		2,601	1,713
Interest expense	2		306		142	491
Other income, net	(191)		(203)		(256)	(304)
Income before income tax expense	1,811		560		2,715	1,526
Income tax expense	927		172		1,284	362
Net income (loss)	884		388		1,431	1,164
Net income (loss) attributable to non-controlling interest	(605)		(420)		(930)	(809)
Net income (loss) attributable to SPAR Group, Inc.	279		(33)		501	354
Depreciation and amortization	146		192		284	352
Capital expenditures	$ 127		$ 40		$ 213	$ 44