Income Taxes - Domestic and Foreign Components of Income Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
United States	$ (38,078)	$ (25,585)	$ (40,774)
(Loss) income before provision for (benefit from) income taxes	(24,174)	(17,690)	(19,939)
Israel
Income Tax Contingency [Line Items]
Foreign	3,163	3,458	15,622
United Kingdom
Income Tax Contingency [Line Items]
Foreign	3,690	2,087	2,345
Netherlands
Income Tax Contingency [Line Items]
Foreign	3,235	1,568	3,104
Australia
Income Tax Contingency [Line Items]
Foreign	686	(1,979)	(2,774)
Germany [Member]
Income Tax Contingency [Line Items]
Foreign	2,900	2,424	2,085
Japan [Member]
Income Tax Contingency [Line Items]
Foreign	$ 230	$ 337	$ 453

The portion of earnings or loss from continuing operations before income taxes that is attributable to domestic operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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The portion of earnings or loss from continuing operations before income taxes that is attributable to foreign operations, which is defined as Income or Loss generated from operations located outside the entity's country of domicile.

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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