Fair Value of Financial Assets and Liabilities - Fair Value Hierarchy For Financial Assets And Liabilities Measured At Fair Value (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	$ 14,970	$ 14,783
Investment in joint venture	39	39
Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	7,710	7,609
Investment in joint venture	0	0
Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	7,237	7,149
Investment in joint venture	0	0
Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	23	25
Investment in joint venture	39	39
Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	2,305	2,095
Cash \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	2,305	2,095
Cash \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Cash \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	4,919	4,454
Cash equivalents \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	4,025	3,861
Cash equivalents \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	894	593
Cash equivalents \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
U.S. government and agency obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	2,058	2,441
U.S. government and agency obligations \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	1,258	1,495
U.S. government and agency obligations \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	800	946
U.S. government and agency obligations \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
U.S. corporate debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	2,373	2,248
U.S. corporate debt securities \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
U.S. corporate debt securities \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	2,373	2,248
U.S. corporate debt securities \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
High yield corporate debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	215	287
High yield corporate debt securities \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
High yield corporate debt securities \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	215	287
High yield corporate debt securities \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	13	20
Asset-backed securities \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Asset-backed securities \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	13	20
Asset-backed securities \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Municipal obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	640	732
Municipal obligations \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Municipal obligations \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	640	732
Municipal obligations \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Auction rate securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	23	25
Auction rate securities \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Auction rate securities \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Auction rate securities \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	23	25
Foreign debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	2,302	2,323
Foreign debt securities \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Foreign debt securities \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	2,302	2,323
Foreign debt securities \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Publicly traded equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	122	158
Publicly traded equity securities \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	122	158
Publicly traded equity securities \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Publicly traded equity securities \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and investments	0	0
Strategic investments held at cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost method strategic investments	385	384
Strategic investments held at cost \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost method strategic investments	0	0
Strategic investments held at cost \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost method strategic investments	0	0
Strategic investments held at cost \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost method strategic investments	385	384
Long-term debt carried at discounted cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt carried at discounted cost	(5,186)	(4,999)
Long-term debt carried at discounted cost \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt carried at discounted cost	0	0
Long-term debt carried at discounted cost \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt carried at discounted cost	(5,186)	(4,999)
Long-term debt carried at discounted cost \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt carried at discounted cost	0	0
Foreign Exchange Contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange derivative assets	74	39
Foreign exchange derivative liabilities	(79)	(78)
Foreign Exchange Contract \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange derivative assets	0	0
Foreign exchange derivative liabilities	0	0
Foreign Exchange Contract \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange derivative assets	74	39
Foreign exchange derivative liabilities	(79)	(78)
Foreign Exchange Contract \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange derivative assets	0	0
Foreign exchange derivative liabilities	0	0
Commodity Contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange derivative liabilities	(6)	(4)
Commodity Contract \| Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange derivative liabilities	0	0
Commodity Contract \| Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange derivative liabilities	(6)	(4)
Commodity Contract \| Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange derivative liabilities	$ 0	$ 0

Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
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-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6506951

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- Definition

Fair value portion of investments accounted under the cost method.

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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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- Definition

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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- Definition

Fair value portion of investments in an entity not consolidated. Includes, but is not limited to, investments in an entity that is affiliated with the reporting entity by means of direct or indirect ownership, an entity in which the reporting entity shares control of the entity with another party or group, an entity which the company has significant influence, but does not have control and subsidiaries that are not required to be consolidated and are accounted for using the equity or cost method.

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