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Related Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Smith, Gambrell & Russell, LLP [Member]
Related Party Transaction [Line Items]
Fees payable to Smith, Gambrell & Russell	$ 0.1	$ 0.2
Amount due to related party	0.0		$ 0.0
European Metal Recycling Limited [Member]
Related Party Transaction [Line Items]
Amount due to related party	0.1		$ 0.0
Tendering process to select best buyer of scrap metal	0.1	$ 0.3
Advan Six [Member]
Related Party Transaction [Line Items]
Amount due to related party	0.0
Tendering process to select best buyer of scrap metal	$ 0.1