Segment Information (Details) $ in Millions		1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 23, 2017 USD ($) director	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2015 segment	Aug. 15, 2017 USD ($)	Jan. 22, 2017	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of reporting segments | segment							3
Non-voting preferred stock, issued		$ 0.0	$ 0.0		$ 0.0					$ 0.0
Segment Reporting Information, Profit (Loss) [Abstract]
Net revenue			9.3	$ 11.5	27.7	$ 32.8
Operating loss from continuing operations			(6.3)	(7.7)	(18.8)	(29.9)
Restructuring and other			(1.2)	(1.3)	(1.1)	(7.1)
Interest income			0.0	0.0	0.0	0.2
Net gains from GBAM Fund activities			1.0	0.0	1.0	0.0
Other income (expense), net			0.1	0.2	(0.6)	(0.8)
Loss from continuing operations before income taxes			(5.2)	(7.5)	(18.4)	(30.5)
Nexsan Business
Segment Reporting Information, Profit (Loss) [Abstract]
Net revenue			9.3	11.5	27.7	32.8
Asset Management Business
Segment Reporting Information, Profit (Loss) [Abstract]
Net revenue			0.0	0.0	0.0	0.0
Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Operating loss from continuing operations			(3.7)	(4.3)	(13.3)	(14.3)
Operating Segments | Nexsan Business
Segment Reporting Information, Profit (Loss) [Abstract]
Operating loss from continuing operations			(2.5)	(4.3)	(10.4)	(14.3)
Operating Segments | Asset Management Business
Segment Reporting Information, Profit (Loss) [Abstract]
Operating loss from continuing operations			(1.2)	0.0	(2.9)	0.0
Corporate and Unallocated
Segment Reporting Information, Profit (Loss) [Abstract]
Operating loss from continuing operations			(1.4)	(2.1)	(4.4)	(8.5)
Segment Reconciling Items
Segment Reporting Information, Profit (Loss) [Abstract]
Restructuring and other			(1.2)	$ (1.3)	(1.1)	$ (7.1)
GBAM Fund
Segment Reporting Information [Line Items]
Investment amount		10.0
NXSN Acquisition Corp
Segment Reporting Information [Line Items]
Noncontrolling interest, percentage held by parent	50.00%								100.00%
Senior secured convertible promissory note	$ 25.0
Noncontrolling interest, percentage held by noncontrolling owners	50.00%
Number of board directors designated to company | director	2
Number of board directors | director	5
Aggregate funded equity commitments		10.0	10.0		10.0			$ 4.7
Increase senior secured convertible promissory note					10.0
Non-voting preferred stock, issued		$ 5.6	$ 5.6		$ 5.6			$ 5.3