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Pension and Other Postretirement Benefits - Additional Information (Detail) | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2016 USD ($) Installments | Sep. 30, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items] |  |
Increase in pension liability, separation transaction |  | $ 845,000,000
Accumulated increase in net actuarial loss after-tax, separation transaction |  | (551,000,000)
Decrease in net periodic benefit cost, separation transaction | $ 5,000,000 |
Cash contribution term to pension plan | 30 months |
Number of installments | Installments | 3 |
Minimum required cash contribution to pension plan | $ 50,000,000 |
Aggregate cash cash contribution to pension plan | 150,000,000 |
Pension Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Change in interest cost component of net periodic benefit cost determination | 22,000,000 | 70,000,000
Other Postretirement Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Change in interest cost component of net periodic benefit cost determination | $ 4,000,000 | $ 12,000,000

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- Definition The estimated reduction in interest cost upon application of change in accounting estimate in next fiscal year. + References No definition available. + Details
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- Definition The increase (decrease) during the reporting period in the amount due to fund retirement benefits to employees, retired and disabled former employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 + Details
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