Financial Instruments - Effect of Interest Rate Swaps on Results of Operations (Detail) $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain Recognized in OCI on Derivatives, Net of Tax	$ (1)
Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain Recognized in OCI on Derivatives, Net of Tax	1
Interest Rate Swaps [Member] \| Reclassification out of Accumulated Other Comprehensive Income into Operations [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate swaps	$ 9

Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121558989&loc=d3e80720-113993

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580

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Balance Type:	credit
Period Type:	duration