Investments - Contractual Maturities of Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Amortized Cost
Amortized Cost	$ 51,177	$ 2,531
Fair Value
Fair Value	51,172	2,417
Unrestricted available-for-sale, Debt securities
Amortized Cost
Amortized Cost, Due in one year or less	50,014
Amortized Cost	50,014	178
Fair Value
Fair Value, Due in one year or less	49,996
Fair Value	49,996	53
Restricted
Amortized Cost
Amortized Cost	1,163	2,353
Fair Value
Fair Value	$ 1,176	$ 2,364

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

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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 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: 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=118954083&loc=d3e26610-111562

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-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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