Restructuring and Other Charges - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) employee	Jun. 30, 2019 USD ($) employee	Jun. 30, 2020 USD ($) employee	Jun. 30, 2019 USD ($) employee
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 105	$ 472	$ 144	$ 516
Restructuring and other charges (benefits) after tax	80	377	114	411
Reversal of impairment charge due to reclassification of assets	7
Reversal of impairment charge due to reclassification of assets, after tax	7
Gain on sale of assets	(2)	(5)	(4)	(7)
Layoff costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	54	15	76	68
Restructuring and other charges (benefits) after tax	38	11	55	52
Pension Settlement and Contribution Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	64		64
Restructuring and other charges (benefits) after tax	$ 53		$ 53
Restructuring Programs Layoffs 2020
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee	2,521,000,000		2,981,000,000
Other exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 2		$ 5
Restructuring and other charges (benefits) after tax	2		5
Reversal of Prior Period Programs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(8)	(3)	(10)	(4)
Restructuring and other charges (benefits) after tax	(6)	(3)	(8)	(4)
UK Forgings
Restructuring Cost and Reserve [Line Items]
Restructuring charges			6
Restructuring and other charges (benefits) after tax	$ 6
Impairments of Assets Associated with Agreement to Sell Aerospace Components Business
Restructuring Cost and Reserve [Line Items]
Restructuring charges			5
Restructuring and other charges (benefits) after tax			5
Sale of Assets
Restructuring Cost and Reserve [Line Items]
Gain on sale of assets			2
Gain on sale of assets, net of tax			$ 2
Impairment of Disks
Restructuring Cost and Reserve [Line Items]
Restructuring charges		428		428
Restructuring and other charges (benefits) after tax		345		$ 345
Asset impairment charges		$ 428
Restructuring Programs Layoffs 2019
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee		220,000,000		901,000,000
Other Exit Costs from Lease Terminations
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 12		$ 12
Restructuring and other charges (benefits) after tax		9		9
Pension Settlement Cost
Restructuring Cost and Reserve [Line Items]
Restructuring charges		2		4
Restructuring and other charges (benefits) after tax		1		3
Impairment of Property, Plant and Equipment
Restructuring Cost and Reserve [Line Items]
Restructuring charges		6		6
Restructuring and other charges (benefits) after tax		$ 5		5
Executive Severance Net of the Benefit of Forfeited Executive Stock Compensation
Restructuring Cost and Reserve [Line Items]
Restructuring charges				2
Restructuring and other charges (benefits) after tax				1
Other Exit Cost Lease Termination Loss
Restructuring Cost and Reserve [Line Items]
Restructuring charges				(3)
Restructuring and other charges (benefits) after tax				(3)
Elimination of Life Insurance Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges				(15)
Restructuring and other charges (benefits) after tax				$ (12)
Fastening Systems | Restructuring Programs Layoffs 2020
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee	1,169,000,000		1,275,000,000
Fastening Systems | Restructuring Programs Layoffs 2019
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee		39,000,000		132,000,000
Engine Products | Restructuring Programs Layoffs 2020
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee	1,116,000,000		1,291,000,000
Engine Products | Impairment of Disks
Restructuring Cost and Reserve [Line Items]
Asset impairment charges		$ 247
Engine Products | Restructuring Programs Layoffs 2019
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee		53,000,000		103,000,000
Engineered Structures | Restructuring Programs Layoffs 2020
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee	200,000,000		300,000,000
Engineered Structures | Impairment of Disks
Restructuring Cost and Reserve [Line Items]
Asset impairment charges		$ 181
Engineered Structures | Restructuring Programs Layoffs 2019
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee		53,000,000		112,000,000
Forged Wheels | Restructuring Programs Layoffs 2020
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee	36,000,000		92,000,000
Forged Wheels | Restructuring Programs Layoffs 2019
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee		6,000,000		60,000,000
Corporate Segment | Restructuring Programs Layoffs 2020
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee			23,000,000
Corporate Segment | Restructuring Programs Layoffs 2019
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee		69,000,000		494,000,000
Small Additive Business
Restructuring Cost and Reserve [Line Items]
Loss on sale of business				$ 12
Loss on sale of business, net of tax				$ 9
Small Additive Business | Engineered Structures
Restructuring Cost and Reserve [Line Items]
Loss on sale of business		$ 12
Loss on sale of business, net of tax		$ 9