SEGMENT AND GEOGRAPHIC DATA Geographic Data Reporting (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenue	$ 121,617	$ 118,108	$ 113,591	$ 103,405	$ 100,314	$ 108,136	$ 113,067	$ 101,227	$ 456,721	$ 422,744	$ 463,197
Long-lived assets, net of accumulated depreciation and amortization	6,337				8,938				6,337	8,938	9,951
Total assets	111,640				101,812				111,640	101,812	124,949
Net assets	43,152				41,885				43,152	41,885	61,180	$ 59,257
Hudson Americas
Segment Reporting Information [Line Items]
Revenue									16,243	15,581	28,668
Long-lived assets, net of accumulated depreciation and amortization	0				2				0	2	36
Total assets	5,892				5,880				5,892	5,880	7,766
Hudson Asia Pacific
Segment Reporting Information [Line Items]
Revenue									282,824	236,839	219,391
Long-lived assets, net of accumulated depreciation and amortization	4,965				7,049				4,965	7,049	7,382
Total assets	56,519				51,331				56,519	51,331	49,246
Hudson Europe
Segment Reporting Information [Line Items]
Revenue									157,978	170,658	215,677
Long-lived assets, net of accumulated depreciation and amortization	1,372				1,528				1,372	1,528	1,859
Total assets	47,066				40,790				47,066	40,790	53,557
Corporate
Segment Reporting Information [Line Items]
Revenue									0	0	0
Long-lived assets, net of accumulated depreciation and amortization	0				359				0	359	674
Total assets	2,163				3,811				2,163	3,811	14,380
Inter- segment elimination
Segment Reporting Information [Line Items]
Revenue									(324)	(334)	(539)
Long-lived assets, net of accumulated depreciation and amortization	0				0				0	0	0
Total assets	0				0				0	0	0
United Kingdom
Segment Reporting Information [Line Items]
Revenue									97,995	116,508	154,931
Long-lived assets, net of accumulated depreciation and amortization	974				1,259				974	1,259	1,707
Net assets	8,403				9,101				8,403	9,101	17,371
Australia
Segment Reporting Information [Line Items]
Revenue									220,292	181,899	159,539
Long-lived assets, net of accumulated depreciation and amortization	4,030				4,023				4,030	4,023	4,115
Net assets	14,396				10,732				14,396	10,732	9,920
CHINA
Segment Reporting Information [Line Items]
Revenue									18,147	16,203	25,401
Long-lived assets, net of accumulated depreciation and amortization	421				2,381				421	2,381	2,835
Net assets	4,956				5,762				4,956	5,762	9,386
United States
Segment Reporting Information [Line Items]
Revenue									15,406	14,690	27,965
Long-lived assets, net of accumulated depreciation and amortization	0				369				0	369	718
Net assets	1,591				4,854				1,591	4,854	13,467
Continental Europe
Segment Reporting Information [Line Items]
Revenue									59,706	53,837	60,248
Long-lived assets, net of accumulated depreciation and amortization	397				261				397	261	144
Net assets	10,468				7,284				10,468	7,284	7,176
Other Asia Pacific
Segment Reporting Information [Line Items]
Revenue									44,385	38,737	34,451
Long-lived assets, net of accumulated depreciation and amortization	515				645				515	645	432
Net assets	3,683				4,279				3,683	4,279	3,875
Other Americas
Segment Reporting Information [Line Items]
Revenue									790	870	662
Long-lived assets, net of accumulated depreciation and amortization	0				0				0	0	0
Net assets	$ (345)				$ (127)				$ (345)	$ (127)	$ (15)