Segment Information - Net Revenue and Operating Income (Loss) by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Net revenue	$ 8.0	$ 8.8	$ 17.4	$ 18.4
Operating income (loss) from continuing operations	(1.7)	(5.2)	(3.3)	(12.7)
Restructuring and other	(0.1)	0.6	(0.1)	0.1
Interest expense	(0.1)	0.0	(0.2)	0.0
Net losses from GBAM Fund activities	(0.4)	0.0	(0.5)	0.0
Other income (expense), net	(0.1)	(0.6)	0.5	(0.5)
Loss from continuing operations before income taxes	(2.3)	(5.8)	(3.5)	(13.2)
Nexsan Business
Segment Reporting Information [Line Items]
Net revenue	8.1	8.8	17.4	18.4
Asset Management Business
Segment Reporting Information [Line Items]
Net revenue	(0.1)	0.0	0.0	0.0
Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss) from continuing operations	(0.8)	(4.4)	(1.6)	(9.6)
Operating Segments | Nexsan Business
Segment Reporting Information [Line Items]
Operating income (loss) from continuing operations	0.1	(3.6)	0.2	(7.9)
Operating Segments | Asset Management Business
Segment Reporting Information [Line Items]
Operating income (loss) from continuing operations	(0.9)	(0.8)	(1.8)	(1.7)
Corporate and Unallocated
Segment Reporting Information [Line Items]
Operating income (loss) from continuing operations	(0.8)	(1.4)	(1.6)	(3.2)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Restructuring and other	$ (0.1)	$ 0.6	$ (0.1)	$ 0.1