Financial Instruments and Fair Value Measurements - Expected Maturity (Details) - Restricted - Short-term bond - Y	Jun. 30, 2020	Dec. 31, 2019
Minimum
Financial instruments and fair value measurements
Measurement input (in years)	0	0
Maximum
Financial instruments and fair value measurements
Measurement input (in years)	3	3

Value of input used to measure 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 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

Name:	us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant