Segment Reporting and Significant Customer Information - Long Lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets
Long-lived assets	$ 3,604	$ 3,790
United States
Revenues from External Customers and Long-Lived Assets
Long-lived assets	2,875	3,035
Rest of the world
Revenues from External Customers and Long-Lived Assets
Long-lived assets	$ 729	$ 755

Long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e9038-108599

Name:	us-gaap_NoncurrentAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant