Investments and Fair Value Measurements - Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets, Fair Value Disclosure [Abstract]
Investments, amortized cost	$ 10,635	$ 22,846
Recurring
Assets, Fair Value Disclosure [Abstract]
Total	10,635	22,846
Recurring \| Certificates of Deposit [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents, fair value disclosure	3,602	4,481
Recurring \| Corporate Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Investments, amortized cost	7,033	18,365
Recurring \| Significant Other Observable Inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Total	10,635	22,846
Recurring \| Significant Other Observable Inputs (Level 2) \| Certificates of Deposit [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents, fair value disclosure	3,602	4,481
Recurring \| Significant Other Observable Inputs (Level 2) \| Corporate Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Investments, amortized cost	$ 7,033	$ 18,365

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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- Definition

Amount 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 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562

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

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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