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Cash Flow Information - Additional Information (Detail) $ / shares in Units, $ in Millions |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended | 14 Months Ended |
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Oct. 02, 2017 $ / shares shares | Oct. 05, 2016 $ / shares shares | Aug. 31, 2016 shares | Jul. 23, 2015 shares | Jul. 22, 2015 shares | Aug. 31, 2016 shares | Aug. 31, 2016 USD ($) shares | Aug. 30, 2016 USD ($) | Jul. 31, 2015 USD ($) shares | Sep. 30, 2014 shares | Jun. 30, 2017 USD ($) shares | Dec. 31, 2017 USD ($) shares | Dec. 31, 2016 USD ($) shares | Dec. 31, 2015 USD ($) shares | Oct. 04, 2016 shares | Dec. 31, 2014 shares
Schedule Of Common Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sales of investments |  |  |  |  |  |  |  |  |  |  |  | $ 890 | $ 280 | $ 40 |  |
Proceeds from sale of company-owned life insurance policies |  |  |  |  |  |  |  |  |  |  |  |  | 457 |  |  |
Proceeds from Divestiture of Businesses |  |  |  |  |  |  |  |  |  |  |  | $ (9) | $ 692 | $ 112 |  |
Depository shares sold (in shares) | shares | 24,022 |  |  |  |  |  |  |  |  | 25,000,000 | 12,958,767 |  |  |  |  |
Interest in preferred stock | 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 |  |  |  |  |  |  |  |  |  | 481,416,537 | 438,519,780 | 1,310,160,141 | 1,300,000,000.0 | 1,216,663,661
Common stock par value (usd per share) | $ / shares |  | $ 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Decrease in common stock due to reverse stock split |  |  |  |  |  |  |  |  |  |  |  |  | $ (877) |  |  |
Treasury stock retirement (in shares) | shares |  |  | 25,000,000 |  |  | 76,000,000 | 76,000,000 |  |  |  |  |  |  |  |  |
Retirement of treasury stock |  |  |  |  |  |  |  | $ 76 |  |  |  |  | 0 |  |  |
Increase in additional paid in capital due to reverse stock split |  |  |  |  |  |  |  |  |  |  |  |  | 877 |  |  |
Common stock conversion transaction value |  |  |  |  |  |  |  |  |  |  |  | $ 0 | 0 | $ 870 |  |
Common stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Common Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retirement of treasury stock |  |  |  |  |  |  | $ 76 | 76 |  |  |  |  | 76 |  |  |
Number of common stock shares issued in a part of acquisition (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  | 87,397,414 |  |
Additional capital |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Common Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retirement of treasury stock |  |  |  |  |  |  | $ 2,563 | $ 2,563 |  |  |  |  | 2,563 |  |  |
RTI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Common Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock conversion transaction value |  |  |  |  |  |  |  |  | $ 870 |  |  |  |  |  |  |
Number of common stock shares issued in a part of acquisition (in shares) | shares |  | 29,000,000 |  | 87,397,414 | 29,132,471 |  |  |  | 29,132,471 |  |  |  |  |  | 87,000,000 |
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 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest in preferred stock | 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 |  |  |

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