SEGMENT AND GEOGRAPHIC DATA - Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) Segment	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | Segment			3
Revenue, from external customers	$ 39,674		$ 74,135	$ 48,704
Inter-segment revenue	0		0	0
Revenue	39,674	$ 24,573	74,135	48,704
Adjusted net revenue, from external customers	15,091		27,809	18,728
Inter-segment adjusted net revenue	0		0	0
Total adjusted net revenue	15,091	8,930	27,809	18,728
EBITDA (loss)	371	(522)	446	(981)
Depreciation and amortization	(113)	(24)	(223)	(48)
Intercompany interest (expense) income, net	0	0	0	0
Intercompany interest (expense) income, net	9	40	19	119
Net income (loss) before provision for income taxes	267	(506)	242	(910)
Provision for income taxes	389	266	567	373
Accounts receivable, net	19,569	12,300	19,569	12,300	$ 13,445
Long-lived assets, net of accumulated depreciation and amortization	3,502	146	3,502	146
Total assets	50,303	44,736	50,303	44,736	$ 45,386
Inter-Segment Elimination
Segment Reporting Information [Line Items]
Revenue, from external customers	0		0	0
Inter-segment revenue	(15)		(15)	(6)
Revenue	(15)	0	(15)	(6)
Adjusted net revenue, from external customers	0		0	0
Inter-segment adjusted net revenue	0		0	0
Total adjusted net revenue	0	0	0	0
EBITDA (loss)	0	0	0	0
Depreciation and amortization	0	0	0	0
Intercompany interest (expense) income, net	0	0	0	0
Intercompany interest (expense) income, net	0	0	0	0
Net income (loss) before provision for income taxes	0	0	0	0
Provision for income taxes	0	0	0	0
Accounts receivable, net	0	0	0	0
Long-lived assets, net of accumulated depreciation and amortization	0	0	0	0
Total assets	0	0	0	0
Hudson Americas | Operating Segments
Segment Reporting Information [Line Items]
Revenue, from external customers	5,366		9,927	5,394
Inter-segment revenue	0		0	0
Revenue	5,366	2,206	9,927	5,394
Adjusted net revenue, from external customers	4,993		9,202	4,753
Inter-segment adjusted net revenue	(15)		(15)	0
Total adjusted net revenue	4,978	1,893	9,187	4,753
EBITDA (loss)	(173)	(918)	(451)	(978)
Depreciation and amortization	(87)	(5)	(173)	(9)
Intercompany interest (expense) income, net	0	0	0	0
Intercompany interest (expense) income, net	0	(2)	0	(2)
Net income (loss) before provision for income taxes	(260)	(925)	(624)	(989)
Provision for income taxes	8	9	17	17
Accounts receivable, net	3,863	1,857	3,863	1,857
Long-lived assets, net of accumulated depreciation and amortization	3,388	24	3,388	24
Total assets	9,386	4,726	9,386	4,726
Hudson Asia Pacific | Operating Segments
Segment Reporting Information [Line Items]
Revenue, from external customers	28,801		54,141	35,784
Inter-segment revenue	15		15	6
Revenue	28,816	18,833	54,156	35,790
Adjusted net revenue, from external customers	6,880		12,638	9,329
Inter-segment adjusted net revenue	15		15	6
Total adjusted net revenue	6,895	4,818	12,653	9,335
EBITDA (loss)	1,003	1,025	1,765	1,362
Depreciation and amortization	(17)	(13)	(31)	(25)
Intercompany interest (expense) income, net	(86)	(73)	(171)	(159)
Intercompany interest (expense) income, net	1	0	2	0
Net income (loss) before provision for income taxes	901	939	1,565	1,178
Provision for income taxes	243	273	437	337
Accounts receivable, net	10,853	7,514	10,853	7,514
Long-lived assets, net of accumulated depreciation and amortization	75	84	75	84
Total assets	18,871	14,349	18,871	14,349
Hudson Europe | Operating Segments
Segment Reporting Information [Line Items]
Revenue, from external customers	5,507		10,067	7,526
Inter-segment revenue	0		0	0
Revenue	5,507	3,534	10,067	7,526
Adjusted net revenue, from external customers	3,218		5,969	4,646
Inter-segment adjusted net revenue	0		0	(6)
Total adjusted net revenue	3,218	2,219	5,969	4,640
EBITDA (loss)	476	300	546	363
Depreciation and amortization	(8)	(5)	(17)	(11)
Intercompany interest (expense) income, net	0	0	0	0
Intercompany interest (expense) income, net	0	0	0	0
Net income (loss) before provision for income taxes	468	295	529	352
Provision for income taxes	123	(7)	140	3
Accounts receivable, net	4,846	2,843	4,846	2,843
Long-lived assets, net of accumulated depreciation and amortization	35	29	35	29
Total assets	8,745	6,928	8,745	6,928
Corporate Segment | Operating Segments
Segment Reporting Information [Line Items]
Revenue, from external customers	0		0	0
Inter-segment revenue	0		0	0
Revenue	0	0	0	0
Adjusted net revenue, from external customers	0		0	0
Inter-segment adjusted net revenue	0		0	0
Total adjusted net revenue	0	0	0	0
EBITDA (loss)	(935)	(929)	(1,414)	(1,728)
Depreciation and amortization	(1)	(1)	(2)	(3)
Intercompany interest (expense) income, net	86	73	171	159
Intercompany interest (expense) income, net	8	42	17	121
Net income (loss) before provision for income taxes	(842)	(815)	(1,228)	(1,451)
Provision for income taxes	15	(9)	(27)	16
Accounts receivable, net	7	86	7	86
Long-lived assets, net of accumulated depreciation and amortization	4	9	4	9
Total assets	$ 13,301	$ 18,733	$ 13,301	$ 18,733