Cash Flow Information - Additional Information (Details) $ / shares in Units, $ in Millions				1 Months Ended		3 Months Ended	12 Months Ended
	Oct. 02, 2017 $ / shares shares	Oct. 05, 2016 $ / shares shares	Aug. 31, 2016 shares	Aug. 31, 2016 USD ($) shares	Sep. 30, 2014 shares	Jun. 30, 2017 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Oct. 04, 2016 shares	Dec. 31, 2015 shares
Schedule Of Common Stock [Line Items]
Sales of investments							$ 9	$ 890	$ 280
Proceeds from sale of company-owned life insurance policies									457
Proceeds from divestiture of businesses							$ 309	$ (9)	692
Depository shares sold (in shares) | shares	24,022				25,000,000	12,958,767
Preferred stock conversion rate per share	0.10				0.10
Conversion of stock, shares converted (in shares) | shares	31,420
Reverse stock split ratio		0.3333
Common stock share outstanding (in shares) | shares		400,000,000					483,270,717			1,300,000,000.0
Common stock par value (usd per share) | $ / shares		$ 1
Treasury stock retirement (in shares) | shares			25,000,000	76,000,000
Retirement of treasury stock									0
Impact of reverse stock split									$ 0
Common stock
Schedule Of Common Stock [Line Items]
Common stock share outstanding (in shares) | shares							483,270,717	481,416,537	438,519,780		1,310,160,141
Treasury stock retirement (in shares) | shares									0
Retirement of treasury stock				$ 76					$ 76
Impact of reverse stock split									877
Additional capital
Schedule Of Common Stock [Line Items]
Retirement of treasury stock				$ 2,563					2,563
Impact of reverse stock split									(877)
Remmele Medical
Schedule Of Common Stock [Line Items]
Proceeds from divestiture of businesses									102
Alcoa Corporation
Schedule Of Common Stock [Line Items]
Sales of investments									145
Proceeds from divestiture of businesses									120
Alcoa Corporation | Electricity Contract
Schedule Of Common Stock [Line Items]
Outstanding notes held by Investment banks, including accrued and unpaid interest						$ 465
Mandatory convertible preferred stock
Schedule Of Common Stock [Line Items]
Depository shares sold (in shares) | shares	24,975,978
Preferred stock conversion rate per share	0.1
Preferred stock conversion price (in usd per share) | $ / shares	$ 1.56996
Conversion of stock, shares converted (in shares) | shares	39,211,286
Exchange Traded Fixed Income and Equity Securities
Schedule Of Common Stock [Line Items]
Sales of investments									130
Restatement Adjustment
Schedule Of Common Stock [Line Items]
Cash payment for a working capital adjustment from prior period acquisition									$ 10