Significant Accounting Policies (Details 6) - $ / shares	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stock Options [Member]
Risk-free interest rate	1.70%		1.70%	2.40%
Expected term	3 years		3 years	3 years
Volatility	34.70%		34.70%	41.30%
Expected dividend	0.00%		0.00%	0.00%
Weighted average grant-date fair value (in dollars per share)	$ 0.56		$ 0.56	$ 0.84
Employee Stock Purchase Plan [Member]
Risk-free interest rate	2.43%	2.09%	2.43%	2.09%
Expected term	6 months	6 months	6 months	6 months
Volatility	32.98%	32.55%	32.98%	32.55%
Expected dividend	0.00%	0.00%	0.00%	0.00%
Weighted average grant-date fair value (in dollars per share)	$ 0.24	$ 0.72	$ 0.24	$ 0.72

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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