Description of Business	12 Months Ended
Dec. 31, 2017
Accounting Policies [Abstract]
Description of Business	Description of Business Ampco-Pittsburgh Corporation and its subsidiaries (the “Corporation”) manufacture and sell highly engineered, high-performance specialty metal products and customized equipment utilized by industry throughout the world. It operates in two business segments, the Forged and Cast Engineered Products segment and the Air and Liquid Processing segment. The Forged and Cast Engineered Products segment historically consisted of Union Electric Steel Corporation (“Union Electric Steel” or “UES”) and Union Electric Steel UK Limited (“UES-UK”). UES is a forged hardened steel roll producer headquartered in Carnegie, Pennsylvania, with three manufacturing facilities in Pennsylvania and one in Indiana. UES-UK is a cast roll producer located in Gateshead, England. In March 2016, UES acquired the stock of Åkers AB and certain of its affiliated companies, including Åkers AB’s 60% equity interest in a Chinese joint venture company (collectively, “Åkers”). Headquartered in Styckebruk, Sweden, Åkers has been a leader in the production of forged and cast rolls since 1806. Collectively doing business as Union Electric Åkers, this portion of the segment produces ingot and forged products and cast products that service a wide variety of industries globally. They specialize in the production of forged hardened steel rolls used mainly for cold rolling by manufacturers of steel, aluminum and other metals and cast rolls for hot and cold strip mills, medium/heavy section mills and plate mills in a variety of iron and steel qualities. In addition, Union Electric Steel produces ingot and open-die forged products (“forged engineered products”) which are used in the oil and gas industry and the aluminum and plastic extrusion industries. In July 2015, UES acquired the assets of Alloys Unlimited & Processing, Inc. (“AUP”) and, in November 2016, the stock of ASW Steel Inc. (“ASW”). AUP is a supplier of specialty tool, alloy, and carbon steel round bar located in Ohio. ASW is a specialty steel producer based in Ontario, Canada. Both acquisitions support the Corporation’s diversification efforts in the open-die forging market. The segment primarily competes with European, Asian and North and South American companies in both domestic and foreign markets and distributes a significant portion of its products through sales offices located throughout the world. The consolidated financial statements of the Corporation include the financial position and results of operations of the acquired companies from their respective dates of acquisition. The Air and Liquid Processing segment includes Aerofin, Buffalo Air Handling and Buffalo Pumps, all divisions of Air & Liquid Systems Corporation (“Air & Liquid”), a wholly owned subsidiary of the Corporation. Aerofin produces custom-engineered finned tube heat exchange coils and related heat transfer products for a variety of industries including OEM/commercial, nuclear power generation and industrial process. Buffalo Air Handling produces large custom-designed air handling systems for institutional (e.g., hospital, university), pharmaceutical and general industrial building markets. Buffalo Pumps manufactures centrifugal pumps for the fossil fuel power generation, marine defense and industrial refrigeration industries. The segment has operations in Virginia and New York with headquarters in Carnegie, Pennsylvania. The segment distributes a significant portion of its products through a common independent group of sales offices located throughout the United States and Canada.

Description of Business

Ampco-Pittsburgh Corporation and its subsidiaries (the “Corporation”) manufacture and sell highly engineered, high-performance specialty metal products and customized equipment utilized by industry throughout the world. It operates in two business segments, the Forged and Cast Engineered Products segment and the Air and Liquid Processing segment.

The Forged and Cast Engineered Products segment historically consisted of Union Electric Steel Corporation (“Union Electric Steel” or “UES”) and Union Electric Steel UK Limited (“UES-UK”). UES is a forged hardened steel roll producer headquartered in Carnegie, Pennsylvania, with three manufacturing facilities in Pennsylvania and one in Indiana. UES-UK is a cast roll producer located in Gateshead, England. In March 2016, UES acquired the stock of Åkers AB and certain of its affiliated companies, including Åkers AB’s 60% equity interest in a Chinese joint venture company (collectively, “Åkers”). Headquartered in Styckebruk, Sweden, Åkers has been a leader in the production of forged and cast rolls since 1806. Collectively doing business as Union Electric Åkers, this portion of the segment produces ingot and forged products and cast products that service a wide variety of industries globally. They specialize in the production of forged hardened steel rolls used mainly for cold rolling by manufacturers of steel, aluminum and other metals and cast rolls for hot and cold strip mills, medium/heavy section mills and plate mills in a variety of iron and steel qualities.

In addition, Union Electric Steel produces ingot and open-die forged products (“forged engineered products”) which are used in the oil and gas industry and the aluminum and plastic extrusion industries. In July 2015, UES acquired the assets of Alloys Unlimited & Processing, Inc. (“AUP”) and, in November 2016, the stock of ASW Steel Inc. (“ASW”). AUP is a supplier of specialty tool, alloy, and carbon steel round bar located in Ohio. ASW is a specialty steel producer based in Ontario, Canada. Both acquisitions support the Corporation’s diversification efforts in the open-die forging market.

The segment primarily competes with European, Asian and North and South American companies in both domestic and foreign markets and distributes a significant portion of its products through sales offices located throughout the world. The consolidated financial statements of the Corporation include the financial position and results of operations of the acquired companies from their respective dates of acquisition.

The Air and Liquid Processing segment includes Aerofin, Buffalo Air Handling and Buffalo Pumps, all divisions of Air & Liquid Systems Corporation (“Air & Liquid”), a wholly owned subsidiary of the Corporation. Aerofin produces custom-engineered finned tube heat exchange coils and related heat transfer products for a variety of industries including OEM/commercial, nuclear power generation and industrial process. Buffalo Air Handling produces large custom-designed air handling systems for institutional (e.g., hospital, university), pharmaceutical and general industrial building markets. Buffalo Pumps manufactures centrifugal pumps for the fossil fuel power generation, marine defense and industrial refrigeration industries. The segment has operations in Virginia and New York with headquarters in Carnegie, Pennsylvania. The segment distributes a significant portion of its products through a common independent group of sales offices located throughout the United States and Canada.