Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Net income (loss)	$ (3.1)	$ (3.5)	$ 6.0	$ (18.5)
Net pension adjustments, net of tax:
Reclassification of adjustment for defined benefit plans recorded in net loss				20.6
Total net pension adjustments				20.6
Total other comprehensive income, net of tax				20.6
Comprehensive income (loss)	(3.1)	(3.5)	6.0	2.1
Less: Comprehensive loss attributable to noncontrolling interest	(0.3)	(0.2)	(0.7)	(0.9)
Comprehensive income (loss) attributable to GlassBridge Enterprises, Inc.	$ (2.8)	$ (3.3)	$ 6.7	$ 3.0