Fair Value Measurements and Available for Sale Investments - Available-for-sale Investments (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 246,029
Gross Unrealized Gains	1,384
Gross Unrealized Losses	(32)
Total Fair Value	247,381
Short-term investments	197,166	$ 203,210
Long-term investments	50,215	$ 54,305
Agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	41,754
Gross Unrealized Gains	139
Gross Unrealized Losses	(3)
Total Fair Value	41,890
Short-term investments	14,900
Long-term investments	$ 27,000
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	$ 5,639
Gross Unrealized Gains	46
Gross Unrealized Losses	0
Total Fair Value	5,685
Short-term investments	5,000
Long-term investments	$ 700
Certificates of deposit \| Minimum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	1 year
Certificates of deposit \| Maximum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	2 years
Commercial and corporate obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 86,805
Gross Unrealized Gains	97
Gross Unrealized Losses	(29)
Total Fair Value	86,873
Short-term investments	82,600
Long-term investments	$ 4,300
Commercial and corporate obligations \| Minimum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	1 year
Commercial and corporate obligations \| Maximum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	2 years
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 111,831
Gross Unrealized Gains	1,102
Gross Unrealized Losses	0
Total Fair Value	112,933
Short-term investments	94,700
Long-term investments	$ 18,200
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

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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).

+ References

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-Publisher FASB
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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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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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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 noncurrent.

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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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