Significant Accounting Policies (Details 2) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Amortized cost	$ 43,234	$ 49,718
Gross unrealized gains	14	0
Gross unrealized losses	(2)	(69)
Fair value	43,246	49,649
Commercial Paper [Member]
Amortized cost	7,970	3,986
Gross unrealized gains	0	0
Gross unrealized losses	(2)	(66)
Fair value	7,968	3,985
Corporate Debt Securities [Member]
Amortized cost	12,346	14,899
Gross unrealized gains	13	0
Gross unrealized losses	0	(1)
Fair value	12,359	14,833
US Government Agencies Debt Securities [Member]
Amortized cost	4,972	6,976
Gross unrealized gains	1	0
Gross unrealized losses	0	(1)
Fair value	4,973	6,975
Short-term Investments [Member]
Amortized cost	21,768	24,536
Gross unrealized gains	14	0
Gross unrealized losses	0	(69)
Fair value	21,782	24,467
Cash [Member]
Amortized cost	7,961	8,391
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Fair value	7,961	8,391
Money Market Funds [Member]
Amortized cost	9,514	14,295
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Fair value	9,514	14,295
Certificates of Deposit [Member]
Amortized cost	471	1,171
Gross unrealized gains	0	0
Gross unrealized losses	0	(1)
Fair value	471	1,170
Cash Equivalents [Member]
Amortized cost	21,466	25,182
Gross unrealized gains	0	0
Gross unrealized losses	(2)	0
Fair value	$ 21,464	$ 25,182

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as 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 (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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+ References

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