Income Taxes - Payment for Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards
Cash paid for taxes	$ 29,199	$ 16,981	$ 8
Domestic
Operating Loss Carryforwards
Cash paid for taxes	1,647	373	8
Foreign
Operating Loss Carryforwards
Cash paid for taxes	$ 27,552	$ 16,608	$ 0

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4297-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3536-108585

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