Financial Instruments (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Financial Instruments (Textuals) [Abstract]
Line Of Credit Facility Forecasted Borrowing Amount	$ 100,000,000
Derivative, Fixed Interest Rate	3.24%
Fair value of derivative liability, other non-current, designated as hedging instrument in cash flow hedge	8,900,000		9,200,000
Interest rate swap Cash Flow Hedge Loss Reclassified To Interest Expense	700,000	700,000
Other Comprehensive Income Unrealized Gain (Loss) On Derivative Arising During Period	300,000	1,000,000
Interest rate swap cash flow hedge gain (loss) to be reclassified within twelve months	(1,900,000)
Foreign currency forward contracts assets fair value	1,000,000		500,000
Foreign currency forward contracts liabilities fair value	300,000		500,000
Net gain from other charges (income)	1,900,000	0
Notional value of other derivatives	$ 204,700,000		$ 143,600,000