Marketable Securities and Fair Value Measurements - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Marketable securities and fair value measurements
Amortized Cost	$ 6,055	$ 121,005
Gross Unrealized Losses	(6)	(201)
Estimated Fair Value	6,049	120,804
Investment securities
Marketable securities and fair value measurements
Amortized Cost	6,055	114,402
Gross Unrealized Losses	(6)	(124)
Estimated Fair Value	$ 6,049	114,278
Investment securities
Marketable securities and fair value measurements
Amortized Cost		6,603
Gross Unrealized Losses		(77)
Estimated Fair Value		$ 6,526

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
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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-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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-Section 45
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