Revenues - Revenues By Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from contract with customers	$ 101,215	$ 79,242
United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customers	77,950	64,752
Other countries
Disaggregation of Revenue [Line Items]
Revenue from contract with customers	$ 23,265	$ 14,490
Geographic Concentration Risk \| Revenue from Contract with Customer
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	100.00%	100.00%
Geographic Concentration Risk \| Revenue from Contract with Customer \| United States
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	77.00%	82.00%
Geographic Concentration Risk \| Revenue from Contract with Customer \| Other countries
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	23.00%	18.00%

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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 32
-Paragraph 2A
-URI http://asc.fasb.org/extlink&oid=82859839&loc=SL82860478-203043

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130543-203045

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130539-203045

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130545-203045

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