Note 9 - Segment Information - Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net revenues	$ 57,160	$ 54,579
Operating income (loss)	1,733	730
Interest expense	199	199
Other income, net	(65)	(72)
Income before income tax expense	1,599	603
Income tax expense	558	178
Net income	1,041	425
Net income (loss) attributable to non-controlling interest	(422)	(301)
Net income attributable to SPAR Group, Inc.	619	124
Depreciation and amortization	508	542
Capital expenditures	464	1,072
US Segment [Member]
Net revenues	18,657	18,369
Operating income (loss)	757	(320)
Interest expense	59	14
Other income, net		30
Income before income tax expense	698	(364)
Income tax expense	201	(12)
Net income	497	(352)
Net income (loss) attributable to non-controlling interest	(97)	89
Net income attributable to SPAR Group, Inc.	400	(263)
Depreciation and amortization	369	382
Capital expenditures	378	635
International Segment [Member]
Net revenues	38,503	36,210
Operating income (loss)	976	1,050
Interest expense	140	185
Other income, net	(65)	(102)
Income before income tax expense	901	967
Income tax expense	357	190
Net income	544	777
Net income (loss) attributable to non-controlling interest	(325)	(390)
Net income attributable to SPAR Group, Inc.	219	387
Depreciation and amortization	139	160
Capital expenditures	$ 86	$ 437