Financial Instruments (Narrative) (Detail) gal in Millions, $ in Millions	3 Months Ended
Mar. 31, 2020 USD ($) gal	Mar. 31, 2019 USD ($)
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Interest Rate Cash Flow Hedge Liability at Fair Value	$ (14)
Derivative Instruments, Gain (Loss) Recognized in Income, Net	(13)	$ (12)
Interest Rate Caps [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Derivative, Notional Amount	8,192
Interest Rate Caps [Member] \| Subsidiaries [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Derivative, Notional Amount	3,000
Interest Rate Swaps [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Derivative, Notional Amount	2,250
Currency Swap [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Derivative, Notional Amount	$ 1,685
Commodity Contracts [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Units Of Gasoline \| gal	15
Purchase [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Derivative, Notional Amount	$ 2,600
Sold [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Derivative, Notional Amount	5,600
Not Designated As Hedging Instruments [Member] \| Commodity Contracts [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Derivative Instruments, Gain (Loss) Recognized in Income, Net	7	(3)
Interest Expense [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Derivative Instruments, Gain (Loss) Recognized in Income, Net	(28)	4
Operating Expense [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Derivative Instruments, Gain (Loss) Recognized in Income, Net	$ 1	$ (5)

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+ References

No definition available.

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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
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-Section 50
-Paragraph 1A
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-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
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