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Segment and Geographic Area Information - Sales by Major Product Grouping (Detail) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Product Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Sales revenue, goods, net | $ 3,271 | $ 3,236 | $ 3,261 | $ 3,192 | $ 2,967 | $ 3,138 | $ 3,234 | $ 3,055 | $ 12,960 | $ 12,394 | $ 12,413
Flat-rolled aluminum |  |  |  |  |  |  |  |  |  |  |
Product Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Sales revenue, goods, net |  |  |  |  |  |  |  |  | 4,992 | 4,864 | 5,253
Fastening systems and rings |  |  |  |  |  |  |  |  |  |  |
Product Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Sales revenue, goods, net |  |  |  |  |  |  |  |  | 2,102 | 2,060 | 2,168
Investment castings |  |  |  |  |  |  |  |  |  |  |
Product Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Sales revenue, goods, net |  |  |  |  |  |  |  |  | 1,983 | 1,870 | 1,812
Other extruded and forged products |  |  |  |  |  |  |  |  |  |  |
Product Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Sales revenue, goods, net |  |  |  |  |  |  |  |  | 1,565 | 1,495 | 1,332
Architectural aluminum systems |  |  |  |  |  |  |  |  |  |  |
Product Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Sales revenue, goods, net |  |  |  |  |  |  |  |  | 1,065 | 1,010 | 951
Aluminum wheels |  |  |  |  |  |  |  |  |  |  |
Product Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Sales revenue, goods, net |  |  |  |  |  |  |  |  | 805 | 689 | 790
Other |  |  |  |  |  |  |  |  |  |  |
Product Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Sales revenue, goods, net |  |  |  |  |  |  |  |  | $ 448 | $ 406 | $ 107

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