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Post-Employment and Other Long-Term Employees Benefits - Pension Plan Asset Allocation Including Fair-Value Measurements (Detail) - USD ($) $ in Millions | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | $ 477 | $ 473 |
Cash and Cash Equivalents [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 11 | 13 |
Equity Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 137 | 128 |
Government Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 13 | 10 |
Corporate Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 125 | 123 |
Investment Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 84 | 87 |
Real Estate [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 12 | 11 |
Other (Mainly Insurance Assets - Contracts and Reserves) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 95 | 101 |
Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 39 | 37 |
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 11 | 13 |
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 6 | 5 |
Fair Value, Inputs, Level 1 [Member] | Government Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 12 | 10 |
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 4 | 4 |
Fair Value, Inputs, Level 1 [Member] | Investment Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 6 | 5 |
Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 342 | 334 |
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 131 | 123 |
Fair Value, Inputs, Level 2 [Member] | Government Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 1 |  |
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 121 | 119 |
Fair Value, Inputs, Level 2 [Member] | Investment Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 78 | 82 |
Fair Value, Inputs, Level 2 [Member] | Real Estate [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 11 | 10 |
Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 96 | 102 | $ 102
Fair Value, Inputs, Level 3 [Member] | Real Estate [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 1 | 1 |
Fair Value, Inputs, Level 3 [Member] | Other (Mainly Insurance Assets - Contracts and Reserves) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | $ 95 | $ 101 |

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