Debt (Details Textual)	3 Months Ended	9 Months Ended		12 Months Ended		9 Months Ended					9 Months Ended						9 Months Ended
	Sep. 30, 2011 USD ($)	Sep. 30, 2011 USD ($)	Sep. 30, 2010 USD ($)	Dec. 31, 2009	Dec. 31, 2010 USD ($)	Sep. 30, 2011 Old European Letter of Credit Facilities [Member] USD ($)	Sep. 30, 2011 Old European Letter of Credit Facilities [Member] EUR (€)	Dec. 31, 2010 Old European Letter of Credit Facilities [Member] USD ($)	Dec. 31, 2010 Old European Letter of Credit Facilities [Member] EUR (€)	Nov. 09, 2009 Old European Letter of Credit Facilities [Member] EUR (€)	Sep. 30, 2011 New European Letter of Credit Facilities [Member] EUR (€)	Sep. 30, 2011 New European Letter of Credit Facilities [Member] USD ($)	Dec. 31, 2010 New European Letter of Credit Facilities [Member] USD ($)	Dec. 31, 2010 New European Letter of Credit Facilities [Member] EUR (€)	Oct. 30, 2010 New European Letter of Credit Facilities [Member]	Oct. 30, 2009 New European Letter of Credit Facilities [Member] EUR (€)	Sep. 30, 2011 Revolving Line of Credit [Member] USD ($)	Sep. 30, 2011 Letter of Credit [Member] USD ($)	Dec. 31, 2010 Letter of Credit [Member] USD ($)	Sep. 30, 2011 Loans Payable [Member]	Dec. 31, 2010 Loans Payable [Member]
Line of Credit Facility [Line Items]
Credit facilities amount outstanding						$ 21,400,000	€ 16,000,000	$ 44,500,000	€ 33,300,000		€ 62,400,000	$ 83,500,000	$ 74,500,000	€ 55,700,000				$ 144,800,000	$ 133,900,000
Line of credit Facility, annual fee						0.875%	0.875%
Line of credit Facility, fronting fees						0.10%	0.10%
Credit facilities remaining borrowing capacity											114,100,000
The maximum aggregate amount of revolving credit facility to be increased																	200,000,000
Line of credit facility utilized capacity											62,400,000
Credit facilities maximum borrowing capacity										110,000,000						125,000,000	500,000,000	300,000,000
Maturity period of credit facilities	1 year	1 year
Letter of Credit Facility fee for utilized capacity											1.35%
Letter of Credit Facility fee for unutilized capacity											0.40%
Maturity period of unsecured letter of credit facility															364 days	364 days
Debt Instrument [Line Items]
Term Loan, interest rate																				2.39%	2.30%
Debt (Textual) [Abstract]
Term loan Face amount	500,000,000	500,000,000
Credit facilities current borrowing capacity	355,200,000	355,200,000			366,100,000
Credit facility interest rate description		Either (1) London Interbank Offered Rate (“LIBOR”) plus 1.75% - 2.50%, as applicable, depending on our consolidated leverage ratio (2) the base rate (which is based on greater of the prime rate most recently announced by the administrative agent under our New Credit Facilities or the Federal Funds rate plus 0.50% or (3) a daily rate equal to the one month LIBOR plus 1.0% plus, as applicable, an applicable margin of 0.75% - 1.50% determined by reference to the ratio of our total debt to consolidated earnings before interest, taxes, depreciation and amortization (“EBITDA”).
Minimum interest rate over and above LIBOR rate under condition one		1.75%
Maximum interest rate over and above LIBOR rate under condition one		2.50%
Interest rate over and above Federal fund rate under condition two		0.50%
Interest rate over and above LIBOR rate to calculate daily rate under condition three		1.00%
Minimum applicable margin for debt to EBITDA under condition three		0.75%
Maximum applicable margin for debt to EBITDA under condition three		1.50%
Credit facility interest rate swaps	335,000,000	335,000,000			350,000,000
Repayment of credit facility	6,300,000	18,750,000	4,261,000
Maturity period of surety and performance bonds bank guarantees and similar obligations in respect of new letter of credit facility is used				up to five years
Credit Facilities, scheduled repayments due in each of the next four quarters	$ 6,300,000	$ 6,300,000