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Debt - Debt (Parenthetical) (Detail) - USD ($) | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2019 | Dec. 31, 2018
Senior Notes, Interest at 2.60% Payable Semiannually, Principal Due on December 1, 2022 [Member] |  |
Debt Instrument [Line Items] |  |
Senior note face amount | $ 1,400,000,000 | $ 1,400,000,000
Senior notes interest rate | 2.60% | 2.60%
Senior note due date | Dec. 01, 2022 | Dec. 01, 2022
Senior Notes, Interest at 3.95% Payable Semiannually, Principal Due on December 1, 2042 [Member] |  |
Debt Instrument [Line Items] |  |
Senior note face amount | $ 1,100,000,000 | $ 1,100,000,000
Senior notes interest rate | 3.95% | 3.95%
Senior note due date | Dec. 01, 2042 | Dec. 01, 2042

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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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