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Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
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Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Gains (losses) on derivative and hedging activities, net | $ (32) | $ (40) | $ (25) | $ 8
ASC 2016-02 [Member] |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Lease assets and liabilities amount |  |  | 28 |
ASU 2017-12 [Member] | Interest Expense [Member] |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Gains (losses) on derivative and hedging activities, net | $ 7 |  | $ 9 |

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- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
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