Financial Instruments (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jul. 23, 2012	Dec. 31, 2011
Financial Instruments (Textuals) [Abstract]
Line Of Credit Facility Forecasted Borrowing Amount	$ 100,000,000		$ 100,000,000
Derivative, Fixed Interest Rate	3.24%		3.24%
Fair value of derivative liability, other non-current, designated as hedging instrument in cash flow hedge	9,100,000		9,100,000			9,200,000
Interest rate swap Cash Flow Hedge Loss Reclassified To Interest Expense	800,000	800,000	1,500,000	1,500,000
Other Comprehensive Income Unrealized Gain (Loss) On Derivative Arising During Period	(300,000)	(1,900,000)	100,000	(900,000)
Interest rate swap cash flow hedge gain (loss) to be reclassified within twelve months			(1,900,000)
Notional Amount of Foreign Currency Cash Flow Hedge Derivatives					72,300,000
Foreign currency forward contracts assets fair value	300,000		300,000			500,000
Foreign currency forward contracts liabilities fair value	300,000		300,000			500,000
Net gain from other charges (income)	1,600,000	4,400,000	300,000	4,400,000
Notional value of other derivatives	$ 240,800,000		$ 240,800,000			$ 143,600,000