Balance sheet components (Details 4) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Finished goods, at vendor managed inventory locations	$ 13.7	$ 6.4

Gross amount of merchandise or materials to which the entity holds the title, but physically at another entity's facilities (for example, but not limited to, work in process may be temporarily at the site of a subcontractor).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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