Goodwill and intangible assets (Schedule of indefinite life assets not subject to amortization) (Details) (Tradenames [Member], USD $) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2012
Tradenames [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Indefinite life assets not subject to amortization, beginning balance	$ 450,432
Currency translation during the year	(5,896)
Indefinite life assets not subject to amortization, ending balance	$ 444,536

Carrying amount of intangible assets, excluding goodwill, which have a projected indefinite period of benefit (hence are not amortized), allocated to the reportable segment. These assets, acquired either individually or as part of a group of assets, in either an asset acquisition or business combination, are assessed at least annually for impairment. Examples may include trade secrets, contractual rights, trade names, and licensing agreements.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16323-109275

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