Fair value as of the balance sheet date of all foreign currency derivative liabilities designated as cash flow hedging instruments.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624163-113959

Name:	us-gaap_ForeignCurrencyCashFlowHedgeLiabilityAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Fair value measurements (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 M	Dec. 31, 2011 D	Dec. 31, 2011 Recurring Fair value	Dec. 31, 2010 Recurring Fair value	Dec. 31, 2011 Recurring Level 2	Dec. 31, 2010 Recurring Level 2
Fair value measurements
Maximum term of original maturity to classify instruments as cash equivalents (in days/months)	3	90
Fair value of financial assets and liabilities
Cross currency hedge			$ 1,011	$ (262)	$ 1,011	$ (262)