Derivative Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Derivative Instruments
Total asset derivatives	$ 1,883	$ 1,120
Derivatives designated as hedging instruments under ASC 815
Derivative Instruments
Total asset derivatives	1,137	687
Derivatives designated as hedging instruments under ASC 815 | Foreign exchange contracts | Other current assets
Derivative Instruments
Total asset derivatives	1,084	545
Derivatives designated as hedging instruments under ASC 815 | Foreign exchange contracts | Other assets
Derivative Instruments
Total asset derivatives	53	142
Derivatives not designated as hedging instruments under ASC 815 | Foreign exchange contracts | Other current assets
Derivative Instruments
Total asset derivatives	$ 746	$ 433