Financial Instruments Financial Instruments Textual (Details) $ in Thousands, € in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($) Rate	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) Rate	Sep. 30, 2014 USD ($)	Sep. 30, 2015 EUR (€) Rate	Dec. 31, 2014 USD ($)
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months			$ 5,000
Designated as Hedging Instrument [Member] | 3.24% $100 Million Interest Rate Swap [Member]
Derivative [Line Items]
Line Of Credit Facility Forecasted Borrowing Amount	$ 100,000		$ 100,000
Derivative, Fixed Interest Rate | Rate	3.24%		3.24%		3.24%
Designated as Hedging Instrument [Member] | 2.52% $50 Million Interest Rate Swap [Member]
Derivative [Line Items]
Line Of Credit Facility Forecasted Borrowing Amount	$ 50,000		$ 50,000
Derivative, Fixed Interest Rate | Rate	2.52%		2.52%		2.52%
Designated as Hedging Instrument [Member] | 2.25% $100 Million Interest Rate Swap [Member]
Derivative [Line Items]
Line Of Credit Facility Forecasted Borrowing Amount	$ 100,000		$ 100,000
Derivative, Fixed Interest Rate | Rate	2.25%		2.25%		2.25%
Designated as Hedging Instrument [Member] | 3.24% $100 Million Interest Rate Swap [Member]
Derivative [Line Items]
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness	$ 0		$ 0
Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Notional Value Local Currency						$ 72,000
Unrealized Gain (Loss) on Foreign Currency Derivatives, Net, before Tax	6,100	$ 500	(18,100)	$ 900
Gain (Loss) on Foreign Currency Cash Flow Hedge Ineffectiveness	0		0
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	335,500		335,500			325,400
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(4,700)	$ 2,000	4,800	$ 3,000
Derivative Maturing in 2015 [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Notional Value Local Currency | €					€ 26.7
Derivative, Notional Amount	29,900		29,900			$ 87,000
Maturing in 2016 [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Notional Value Local Currency	66,500		66,500
Derivative, Notional Amount	$ 74,500		$ 74,500