CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net earnings (loss)	$ (102.6)	$ (6.8)	$ 5.4
Other comprehensive income (loss):
Currency translation adjustments	(2.3)	(6.0)	0.0
Pension benefit adjustments	(5.1)	7.1	0.0
Deferred tax benefit (expense) on pension benefit adjustments	1.5	(2.1)	0.0
Comprehensive income (loss)	(108.7)	(7.8)	5.4
Amortization of net actuarial gains	(0.3)	0.0	0.0
Income tax on amortization of net actuarial gains	0.1	0.0	0.0
Comprehensive income (loss) attributable to noncontrolling interest	0.3	0.1	(0.1)
Comprehensive income (loss) attributable to Real Industry, Inc.	$ (109.0)	$ (7.9)	$ 5.5