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Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
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 | $ 80 | $ 70 | $ 64
Accrued benefit liabilities | 21 | 29 |
Pension Plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Combined accumulated benefit obligation of pension plans | 120 | 126 |
Plan assets of pension plans | 117 | 120 |
Unfunded benefit obligation | 3 | 6 |
Other Postretirement Plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Unfunded benefit obligation | $ 18 | $ 23 |

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- Definition Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of benefit obligation for defined benefit plan with benefit obligation in excess of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2417-114920 + Details
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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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