Debtor-In-Possession Financial Information - Liabilities subject to compromise (Detail) $ in Millions	Dec. 31, 2017 USD ($)
Liabilities subject to compromise
Trade accounts payable	$ 16.7
Accrued dividends on Redeemable Preferred Stock	1.8
Other accrued liabilities	3.2
Liabilities subject to compromise	340.7
Real Industry
Liabilities subject to compromise
Trade accounts payable	0.1
Accrued dividends on Redeemable Preferred Stock	1.8
Other accrued liabilities	1.2
Liabilities subject to compromise	3.1
Real Alloy
Liabilities subject to compromise
Trade accounts payable	16.6
Other accrued liabilities	2.0
Liabilities subject to compromise	337.6
Senior Secured Notes and Roll Up Debtor-in-Possession Term Notes
Liabilities subject to compromise
Accrued interest	14.0
Senior Secured Notes and Roll Up Debtor-in-Possession Term Notes | Real Alloy
Liabilities subject to compromise
Accrued interest	14.0
Senior Secured Notes
Liabilities subject to compromise
Principal amount outstanding	135.0
Senior Secured Notes | Real Alloy
Liabilities subject to compromise
Principal amount outstanding	135.0
Roll Up DIP Term Notes
Liabilities subject to compromise
Principal amount outstanding	170.0
Roll Up DIP Term Notes | Real Alloy
Liabilities subject to compromise
Principal amount outstanding	$ 170.0