Discontinued Operations and Disposition - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2019	May 31, 2019	Mar. 31, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Oct. 31, 2018
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Proceeds from purchase agreement					$ 0	$ 7,200
Impairment loss			$ 10,082
Proceeds from sale of Avonmore Plant		$ 3,700			$ 3,700	0
Vertical Seal [Member] | Sale not Qualified as Discontinued Operation [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Purchase price, after estimated purchase price adjustments							$ 7,200
ASW Steel Inc [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Asset write down charge						15,000
Proceeds from purchase agreement	$ 8,000
Purchase price, after estimated purchase price adjustments	$ 4,292			$ 4,292
Net sales				35,045		63,740
ASW Steel Inc [Member] | Union Electric Steel Corporation [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net sales				$ 4,381		$ 22,805