Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Cash	$ 27,046	$ 33,238
Time deposits	3,971	3,924
Money Market Funds (level 1)	155,113	149,624
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value	1,017,852	1,040,678
Total	1,203,982	1,227,464
Included in Cash and cash equivalents	306,701	508,196
Restricted Cash Equivalents, Noncurrent	9,409	9,405
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	316,110	517,601	$ 760,954	$ 366,753
Included in Marketable securities	$ 887,872	$ 709,863

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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Amount of investment in marketable security, classified as current.

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