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Fair Value Measurements and Available for Sale Investments - Available-for-sale Investments (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 64,050	$ 160,540
Gross Unrealized Gains	37	208
Gross Unrealized Losses	(6)	(5)
Total Fair Value	64,081	160,743
Short-term investments	58,597	143,197
Long-term investments	5,484	17,546
Agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,003	21,169
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(6)	(1)
Total Fair Value	4,997	21,169
Short-term investments	$ 0	10,000
Investments outstanding, maturity date range (in years)	1 year
Long-term investments	$ 5,000	$ 11,200
Agency securities | Minimum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	1 year	1 year
Agency securities | Maximum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	2 years	2 years
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,589	$ 2,427
Gross Unrealized Gains	2	9
Gross Unrealized Losses	0	0
Total Fair Value	1,591	2,436
Short-term investments	$ 1,100	1,100
Investments outstanding, maturity date range (in years)	1 year
Long-term investments	$ 500	$ 1,300
Certificates of deposit | Minimum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	1 year	1 year
Certificates of deposit | Maximum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)	2 years	2 years
Commercial and corporate obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 11,778	$ 29,414
Gross Unrealized Gains	1	28
Gross Unrealized Losses	0	(1)
Total Fair Value	$ 11,779	29,441
Short-term investments		29,400
Long-term investments		$ 0
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)	1 year	2 years
US Treasury Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 45,680	$ 107,530
Gross Unrealized Gains	34	170
Gross Unrealized Losses	0	(3)
Total Fair Value	$ 45,714	107,697
Short-term investments		102,700
Long-term investments		$ 5,000
US Treasury Securities | Minimum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)		1 year
US Treasury Securities | Maximum
Debt Securities, Available-for-sale [Line Items]
Investments outstanding, maturity date range (in years)		2 years

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