Derivative Financial Instruments (Fair Value of Derivatives) (Detail) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative Liability		$ 18	$ 27
Other Current Liabilities [Member]
Derivative [Line Items]
Derivative Liability	[1]	2	2
Other Noncurrent Liabilities [Member]
Derivative [Line Items]
Derivative Liability	[2]	16	25
Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative Liability		2	2
Interest Rate Contract [Member] | Other Noncurrent Liabilities [Member]
Derivative [Line Items]
Derivative Liability		16	25
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Liability		11	16
Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative Liability	[1]	1	1
Designated as Hedging Instrument [Member] | Other Noncurrent Liabilities [Member]
Derivative [Line Items]
Derivative Liability	[2]	10	15
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative Liability		1	1
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Noncurrent Liabilities [Member]
Derivative [Line Items]
Derivative Liability		10	15
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Liability		7	11
Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative Liability	[1]	1	1
Not Designated as Hedging Instrument [Member] | Other Noncurrent Liabilities [Member]
Derivative [Line Items]
Derivative Liability	[2]	6	10
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative Liability		1	1
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Noncurrent Liabilities [Member]
Derivative [Line Items]
Derivative Liability		$ 6	$ 10

[1] Current derivative liabilities are presented in other current liabilities in the Consolidated Balance Sheets.

[2] Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in the Consolidated Balance Sheets.