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Post-Employment and Other Long-Term Employees Benefits - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected amortization of actuarial losses in year 2018 | $ 9 |  |
Pension plans with accumulated benefit obligations in excess of plan assets, accumulated benefit obligation | 853 | $ 738 |
Pension plans with accumulated benefit obligations in excess of plan assets, fair value of plan assets | 511 | 443 |
Accrued benefits related to defined contribution pension plans | 19 | 16 |
Annual cost of defined contribution plans | 74 | 70 | $ 70
Pension Benefits [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Pension plans with benefit obligations in excess of plan assets, benefit obligation | 961 | 811 |
Pension plans with benefit obligations in excess of plan assets, fair value of plan assets | 511 | 464 |
Employer contributions | 27 | $ 27 |
Expected contribution in cash | $ 26 |  |

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