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Business Segments - Schedule of Financial Information for Corporation's Reportable Segments (Parenthetical) (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jan. 31, 2026	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025	Jun. 30, 2026	Dec. 31, 2025	Dec. 31, 2024
Revenue from External Customer [Line Items]
Restructuring charges			$ 3,069		$ 9,819
Investments in joint ventures		$ 835		$ 835			$ 835
Deconsolidation Charge				875
Noncurrent asbestos-related insurance receivables		92,942		92,942			107,838
Employee retention credits					735
Location, Statement of Income, Balance [Axis]: us-gaap:DepreciationAndAmortization
Revenue from External Customer [Line Items]
Accelerated depreciation			2,407		3,061
Union Electric Steel U K Limited [Member]
Revenue from External Customer [Line Items]
Estimated recovery distributed	$ 1,255
Estimated recovery under credit agreement		5,370		5,370		$ 5,370	7,500
Asbestos Claims [Member]
Revenue from External Customer [Line Items]
Insurance receivable - asbestos		$ 111,942	124,947	111,942	124,947		126,838	$ 139,295
U.S. [Member]
Revenue from External Customer [Line Items]
Restructuring charges			816		816
Deconsolidation Charge				$ 875
Employee retention credits					735
Non-US [Member]
Revenue from External Customer [Line Items]
Restructuring charges			$ 2,253		$ 9,003
Sales Revenue, Net [Member] \| Individual Foreign Countries [Member] \| Maximum [Member]
Revenue from External Customer [Line Items]
Net sales		10.00%	10.00%	10.00%	10.00%
Forged and Cast Engineered Products [Member]
Revenue from External Customer [Line Items]
Investments in joint ventures		$ 835		$ 835			835
Estimated recovery under credit agreement		$ 5,370		$ 5,370			$ 7,500
Employee retention credits					$ 456
Air and Liquid Processing [Member]
Revenue from External Customer [Line Items]
Employee retention credits					$ 279