Financial Instruments and Derivative Instruments (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Derivative instruments
Percentage of projected intercompany purchases hedged by forward exchange contracts	50.00%
Period of projected intercompany purchase transactions	12 months
Notional amounts of foreign currency purchase contracts	$ 7.5
High end of range
Derivative instruments
Average volume of foreign currency contracts	15
Low end of range
Derivative instruments
Average volume of foreign currency contracts	$ 5

Aggregate notional amount of all foreign currency derivatives not designated as hedging instruments. Notional amount refers to the number of currency units specified in the foreign currency derivative contract.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

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