Concentrations of risk and segment information - Schedule of Revenue by Geographic Segment (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue, Major Customer [Line Items]
Revenue	$ 400,340	$ 279,971	$ 1,183,368	$ 760,292
Americas [Member]
Revenue, Major Customer [Line Items]
Revenue	190,839	204,893	583,282	482,769
Europe, Middle East and Africa [Member]
Revenue, Major Customer [Line Items]
Revenue	156,639	56,068	432,904	207,285
Asia and Pacific Area Countries [Member]
Revenue, Major Customer [Line Items]
Revenue	$ 52,862	$ 19,010	$ 167,182	$ 70,238

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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