Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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

Debt (European Letter of Credit Facilities) (Details) (European Letter of Credit Facilities [Member])	3 Months Ended
	Mar. 31, 2013 USD ($)	Mar. 31, 2013 EUR (€)	Dec. 31, 2012 USD ($)	Dec. 31, 2012 EUR (€)	Oct. 30, 2012	Oct. 30, 2009 EUR (€)
Line of Credit Facility [Line Items]
Maturity period of unsecured letter of credit facility					364 days	364 days
Maximum borrowing capacity						€ 125,000,000
Maturity period of surety and performance bonds bank guarantees	5 years	5 years
Amount outstanding	$ 81,500,000	€ 63,600,000	$ 83,300,000	€ 63,100,000