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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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.

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- Definition

Any certificate of deposit or savings account held by a bank or other financial institution for a short-term specified period of time. Because of their short-term, time deposits are considered 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. 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.

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Fair Value of Financial Instruments - Cash and Cash Equivalents (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	$ 1,131,046	$ 1,247,652	$ 1,394,687	$ 1,260,842
Total short-term investments	86,491	26,337
Cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	1,131,046	1,247,652
Total short-term investments	86,491	26,337
Total	1,217,537	1,273,989
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	1,131,132	1,247,719
Total short-term investments	86,563	26,362
Total	1,217,695	1,274,081
Cash and Cash Equivalents \| Cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and overnight deposits	584,552	590,317
Corporate commercial paper	506,872	629,923
Time deposits	39,622	27,412
Cash and Cash Equivalents \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and overnight deposits	584,552	590,317
Corporate commercial paper	506,958	629,990
Time deposits	39,622	27,412
Short-term Investments \| Cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Corporate commercial paper	86,449	26,296
Time deposits	42	41
Short-term Investments \| Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Corporate commercial paper	86,521	26,321
Time deposits	$ 42	$ 41