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Financial Instruments and Risk Management - Fair Value Information on Other Financial Assets and Liabilities Recorded at Amortized Cost (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 3,006	$ 2,597
Short-term, deposits	581	4
Estimate Fair Value [Member] | Senior Unsecured Convertible Bonds Issued on July 3, 2017 Tranche A [Member]
Long-term debt
Senior unsecured convertible bonds		1,030
Estimate Fair Value [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	2,637	1,691
Short-term, deposits	581	4
Estimate Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | Senior Unsecured Convertible Bonds Issued on July 3, 2017 Tranche B [Member]
Long-term debt
Senior unsecured convertible bonds	1,359	1,073
Estimate Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | Senior Unsecured Convertible Bonds Issued on August 4, 2020 [Member]
Long-term debt
Senior unsecured convertible bonds	1,835	0
Estimate Fair Value [Member] | Fair Value, Inputs, Level 2 [Member]
Long-term debt
Bank loans (including current portion)	583	718
Estimate Fair Value [Member] | Fair Value, Inputs, Level 3 [Member] | Senior Unsecured Convertible Bonds Issued on July 3, 2017 Tranche A [Member]
Long-term debt
Senior unsecured convertible bonds		1,030
Carrying Amount [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	2,637	1,691
Short-term, deposits	581	4
Carrying Amount [Member] | Fair Value, Inputs, Level 1 [Member] | Senior Unsecured Convertible Bonds Issued on July 3, 2017 Tranche B [Member]
Long-term debt
Senior unsecured convertible bonds	674	654
Carrying Amount [Member] | Fair Value, Inputs, Level 1 [Member] | Senior Unsecured Convertible Bonds Issued on August 4, 2020 [Member]
Long-term debt
Senior unsecured convertible bonds	1,364	0
Carrying Amount [Member] | Fair Value, Inputs, Level 2 [Member]
Long-term debt
Bank loans (including current portion)	$ 583	718
Carrying Amount [Member] | Fair Value, Inputs, Level 3 [Member] | Senior Unsecured Convertible Bonds Issued on July 3, 2017 Tranche A [Member]
Long-term debt
Senior unsecured convertible bonds		$ 700

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of loans from a bank with maturities initially due after one year or beyond the normal operating cycle if longer.

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