Business Segment Information and Geographic Data - Net Revenue and Operating Income (Loss) by Segment (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net revenue		$ 36.5	$ 44.1
Operating loss from continuing operations		(29.3)	(35.0)
Goodwill impairment		(3.8)	0.0
Intangibles assets impairment	$ (2.7)	(2.7)	0.0
Restructuring and other		(1.9)	(7.6)
Interest income		0.0	0.2
Net gains from GBAM Fund activities		1.2	0.0
Other income (expense), net		(0.6)	(4.9)
Loss from continuing operations before income taxes		(28.7)	(39.7)
Operating Segments
Segment Reporting Information [Line Items]
Net revenue		36.5	44.1
Operating loss from continuing operations		(16.3)	(17.5)
Operating Segments | Nexsan Corporation
Segment Reporting Information [Line Items]
Net revenue		36.5	44.1
Operating loss from continuing operations		(12.0)	(17.5)
Operating Segments | Asset Management Business
Segment Reporting Information [Line Items]
Net revenue		0.0	0.0
Operating loss from continuing operations		(4.3)	0.0
Corporate and unallocated
Segment Reporting Information [Line Items]
Operating loss from continuing operations		(4.6)	(9.9)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Goodwill impairment		(3.8)	0.0
Intangibles assets impairment		(2.7)	0.0
Restructuring and other		$ (1.9)	$ (7.6)