Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net revenue	$ 8.0	$ 8.8	$ 17.4	$ 18.4
Cost of goods sold	4.1	4.7	8.6	9.9
Gross profit	3.9	4.1	8.8	8.5
Operating expenses:
Selling, general and administrative	4.7	7.7	9.9	16.6
Research and development	0.7	2.2	1.9	4.7
GBAM Fund expenses	0.1	0.0	0.2	0.0
Restructuring and other	0.1	(0.6)	0.1	(0.1)
Total operating expenses	5.6	9.3	12.1	21.2
Operating loss from continuing operations	(1.7)	(5.2)	(3.3)	(12.7)
Other income (expense):
Interest expense	(0.1)	0.0	(0.2)	0.0
Net gain (loss) from GBAM Fund activities	(0.4)	0.0	(0.5)	0.0
Other income (expense), net	(0.1)	(0.6)	0.5	(0.5)
Total other income (expense)	(0.6)	(0.6)	(0.2)	(0.5)
Loss from continuing operations before income taxes	(2.3)	(5.8)	(3.5)	(13.2)
Income tax benefit (provision)	0.0	(0.1)	(0.1)	0.0
Loss from continuing operations	(2.3)	(5.9)	(3.6)	(13.2)
Gain (loss) from discontinued operations, net of income taxes	0.7	(1.2)	0.3	(3.2)
Net loss including noncontrolling interest	(1.6)	(7.1)	(3.3)	(16.4)
Less: Net loss attributable to noncontrolling interest	(0.3)	(2.0)	(0.3)	(3.5)
Net loss attributable to GlassBridge Enterprises, Inc.	$ (1.3)	$ (5.1)	$ (3.0)	$ (12.9)
Loss per common share attributable to GlassBridge common shareholders — basic and diluted:
Continuing operations (in dollars per share)	$ (0.39)	$ (0.78)	$ (0.65)	$ (2.16)
Discontinued operations (in dollars per share)	0.14	(0.24)	0.06	(0.71)
Net loss (in dollars per share)	$ (0.25)	$ (1.02)	$ (0.59)	$ (2.87)
Weighted average common shares outstanding:
Basic and diluted (in shares)	5.1	5.0	5.1	4.5