Cash Equivalents and Investments - Schedule of Cash Equivalents and Available For Sale Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 99,433	$ 141,934
Gains	372	83
Losses	(8)	(1)
Estimated Fair Value	99,797	142,016
Cash equivalents	34,541	13,897
Short-term investments	65,256	120,089
Long-term investments	0	8,030
Total cash equivalents and available-for-sale investments	99,797	142,016
U.S. government securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	56,032	77,329
Gains	371	72
Losses	0	(1)
Estimated Fair Value	56,403	77,400
Corporate notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,860	14,955
Gains	1	11
Losses	(8)
Estimated Fair Value	8,853	14,966
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		35,753
Estimated Fair Value		35,753
Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	34,541	13,897
Estimated Fair Value	$ 34,541	$ 13,897

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

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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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Amount of 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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