Segment Reporting and Significant Customer Information - Revenue for Individual Countries that Exceed 10% of Total Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Revenue, Major Customer [Line Items]
Total revenues	$ 20,327	$ 29,160
United States
Revenue, Major Customer [Line Items]
Total revenues	11,515	16,895
United Kingdom
Revenue, Major Customer [Line Items]
Total revenues	5,113	5,859
Germany
Revenue, Major Customer [Line Items]
Total revenues	2,015	3,641
Rest of the world
Revenue, Major Customer [Line Items]
Total revenues	$ 1,684	$ 2,765

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration