Fair Value Measurements - Unobservable Data Used in Recurring Valuations of Level 3 (Detail) $ in Millions	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Interest Rate Swaps [Member]
Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Derivative financial instruments, Fair Value	$ 348	$ 210
Cross-Currency Interest Rate Swaps [Member]
Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Derivative financial instruments, Fair Value	(461)	(575)
Other [Member]
Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Derivative financial instruments, Fair Value		$ (1)
Level 3 [Member]
Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Derivative financial instruments, Fair Value	(470)
Level 3 [Member] \| Cross-Currency Interest Rate Swaps [Member]
Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Derivative financial instruments, Fair Value	$ (461)
Derivative Asset (Liability) Net, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Derivatives	0.05
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Level 3 [Member] \| Prime/LIBOR Basis Swaps [Member] \| Interest Rate Swaps [Member]
Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Derivative financial instruments, Fair Value	$ (9)
Derivative Asset (Liability) Net, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Level 3 [Member] \| Prime/LIBOR Basis Swaps [Member] \| Interest Rate Swaps [Member] \| Constant Prepayment Rate [Member]
Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Derivatives	0.09
Level 3 [Member] \| Prime/LIBOR Basis Swaps [Member] \| Interest Rate Swaps [Member] \| Bid/ask adjustment to discount rate [Member]
Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Derivatives	0.0008

Value of input used to measure net derivative asset (liability).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-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

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Indicates measurement input for net derivative asset (liability).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Indicates valuation technique for measuring net derivative asset (liability).

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Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=117331979&loc=d3e41228-113958

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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