Subsequent Events - Real Alloy Bankruptcy (Detail) - Asset Purchase Agreement - USD ($) $ in Millions	Mar. 07, 2018	Feb. 02, 2018	Mar. 27, 2018
Noteholder Group
Bankruptcy proceedings
Estimated total purchase consideration offered under the proposed asset purchase agreement	$ 364.0
RA Acquisition Purchaser LLC | Subsequent Event
Bankruptcy proceedings
Estimated total purchase consideration offered under the proposed asset purchase agreement			$ 364.0
Maximum | Noteholder Group
Bankruptcy proceedings
Estimated amount of liabilities to be assumed by the buyer	$ 18.6
Percentage of priority debtor claims that may be recovered as an upfront payment at closing in exchange for terms including negotiated credit limits, volume, and pricing	100.00%
Maximum | Noteholder Group | Subsequent Event
Bankruptcy proceedings
Estimated amount of liabilities to be assumed by the buyer		$ 18.6
Percentage of priority debtor claims that may be recovered as an upfront payment at closing in exchange for terms including negotiated credit limits, volume, and pricing		100.00%