Inventories - Additional Information (Details) $ in Millions	3 Months Ended
Jun. 30, 2018 USD ($) plant	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Inventory [Line Items]
Inventories valued on a LIFO basis		$ 1,257	$ 1,292
Total inventories valued on an average-cost basis		$ 445	$ 530
Engineered Products and Forgings
Inventory [Line Items]
Inventory adjustment recorded in cost of goods sold and inventories	$ 23
Number of plants with inventory adjustments \| plant	1

Number Of Plants

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- Definition

Amount of inventory reserves for last-in first-out (LIFO) and other inventory valuation methods.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=116847112&loc=d3e4492-108314

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount by which inventory stated at last-in first-out (LIFO) is less than (in excess of) inventory stated at other inventory cost methods.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(c))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

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+ References

No definition available.

+ Details

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- Definition

The amount of LIFO (last in first out) inventory present at the reporting date when inventory is also valued using different valuation methods.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6361739&loc=d3e7789-107766

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