Significant Accounting Policies - Cash, Cash Equivalents and Short-term Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents
Significant Accounting Policies [Line Items]
Amortized Cost	$ 10,712	$ 4,789
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	10,712	4,789
Cash and Cash Equivalents \| Money Market Funds
Significant Accounting Policies [Line Items]
Amortized Cost	10,712	4,789
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	10,712	4,789
Marketable Securities
Significant Accounting Policies [Line Items]
Amortized Cost	34,113	41,510
Gross Unrealized Gains	4	23
Gross Unrealized Losses		(2)
Fair Value	34,117	41,531
Marketable Securities \| US Treasury securities
Significant Accounting Policies [Line Items]
Amortized Cost	34,113	41,510
Gross Unrealized Gains	4	23
Gross Unrealized Losses		(2)
Fair Value	34,117	41,531
Short-term Deposits
Significant Accounting Policies [Line Items]
Amortized Cost	30,053	10,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	30,053	10,000
Short-term Deposits \| Term Bank Deposits
Significant Accounting Policies [Line Items]
Amortized Cost	30,053	10,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 30,053	$ 10,000

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).

+ References

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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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