Short-Term Investments - Summary of Short-term Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 1,498	$ 42,163
Gross Unrealized Loss	(2)	(17)
Fair Value	1,496	42,146
Corporate Bonds and Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,498	37,168
Gross Unrealized Loss	(2)	(17)
Fair Value	$ 1,496	37,151
U.S. Government Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		4,995
Fair Value		$ 4,995

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
-Publisher FASB
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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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