Cash, Cash Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Cash and cash equivalents
Amortized Cost	$ 11,080	$ 2,594
Gross Unrealized Gains	0	0
Gross Unrealized Loss	0	0
Fair Value	11,080	2,594
Cash and cash equivalents \| Money market funds
Amortized Cost	11,080	2,594
Gross Unrealized Gains	0	0
Gross Unrealized Loss	0	0
Fair Value	11,080	2,594
Marketable securities
Amortized Cost	35,806	39,776
Gross Unrealized Gains	39	0
Gross Unrealized Loss	0	(6)
Fair Value	35,845	39,770
Marketable securities \| US Treasury securities
Amortized Cost	35,806	39,776
Gross Unrealized Gains	39	0
Gross Unrealized Loss	0	(6)
Fair Value	35,845	39,770
Short-term deposits
Amortized Cost	41,328	70,438
Gross Unrealized Gains	0	0
Gross Unrealized Loss	0	0
Fair Value	41,328	70,438
Short-term deposits \| Term bank deposits
Amortized Cost	41,328	70,438
Gross Unrealized Gains	0	0
Gross Unrealized Loss	0	0
Fair Value	$ 41,328	$ 70,438

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).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
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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).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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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
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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Amount of investment in debt security measured at amortized cost (held-to-maturity), investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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