Foreign Currency Exchange Rate Risk Foreign Currency Exchange Rate Risk (Details textual) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Derivative [Line Items]
Net gain (loss)	$ 1.5	$ 1.2
Maturities of foreign currency forward contracts	3 months

Net Increase or Decrease in the fair value of the derivative or group of derivatives included in earnings.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5618551-113959

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