Fair Value Measurements and Available for Sale Investments - Available-for-sale Investments (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 170,067
Gross Unrealized Gains	961
Gross Unrealized Losses	(1)
Total Fair Value	171,027
Short-term investments	156,706	$ 203,210
Long-term investments	14,321	$ 54,305
Agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	16,607
Gross Unrealized Gains	52
Gross Unrealized Losses	(1)
Total Fair Value	16,658
Short-term investments	10,100
Long-term investments	$ 6,500
Agency securities \| Minimum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	1 year
Agency securities \| Maximum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	2 years
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 4,683
Gross Unrealized Gains	41
Gross Unrealized Losses	0
Total Fair Value	$ 4,724
Certificates of deposit \| Maximum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	1 year
Commercial and corporate obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 45,961
Gross Unrealized Gains	225
Gross Unrealized Losses	0
Total Fair Value	$ 46,186
Commercial and corporate obligations \| Maximum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	1 year
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 102,816
Gross Unrealized Gains	643
Gross Unrealized Losses	0
Total Fair Value	103,459
Short-term investments	95,700
Long-term investments	$ 7,800
U.S. Treasury securities \| Minimum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	1 year
U.S. Treasury securities \| Maximum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	2 years

Available-for-sale Debt Securities, Remaining Maturity

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- Definition

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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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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