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Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employee waiting period after hire to participate in the defined contribution plans | 90 days |  |
Employee maximum contribution towards defined contribution plans as percentage of annual compensation | 50.00% |  |
Employee maximum contribution towards defined contribution plans as percentage of annual incentive plan bonus | 80.00% |  |
Percentage of contribution upon eligibility for non union employees hired after threshold period | 3.00% |  |
Employer's match in cash of non-union employee contributions on first specified percentage of eligible compensation | 100.00% |  |
First percentage of eligible compensation on which specified percentage of non-union employee contribution is matched by the employer in cash | 3.00% |  |
Employer's match in cash of non-union employee contributions on next specified percentage of eligible compensation | 50.00% |  |
Next percentage of eligible compensation on which specified percentage of non-union employee contribution is matched by the employer in cash | 3.00% |  |
Employer maximum match of non-union employee contribution on eligible compensation | 4.50% |  |
Defined contribution plans expense | $ 88 | $ 80 | $ 70
Accrued benefit liabilities | 19 | 21 |
Pension Plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Combined accumulated benefit obligation of pension plans | 141 | 120 |
Plan assets of pension plans | 136 | 117 |
Unfunded benefit obligation | 5 | 3 |
Other Postretirement Plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Unfunded benefit obligation | $ 14 | $ 18 |

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