Financial Instruments Financial Instruments Textual (Details) $ in Thousands, € in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) Rate	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) Rate	Jun. 30, 2015 USD ($)	Jun. 30, 2016 EUR (€) Rate	Dec. 31, 2015 USD ($)
Derivative [Line Items]
swiss franc per euro floor	1.2		1.2		1.2
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months			$ 2,100
Designated as Hedging Instrument [Member] | 3.24% $100 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	67,000		67,000		€ 36.3
Derivative, Notional Amount	40,000		40,000			$ 73,000
Unrealized Gain (Loss) on Foreign Currency Derivatives, Net, before Tax	0	$ 1,000	(200)	$ 24,200
Gain (Loss) on Foreign Currency Cash Flow Hedge Ineffectiveness	0		0
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	348,400		348,400			318,700
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	$ 1,700	$ 200	$ 600	$ 9,500
Derivative Maturing in 2015 [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Derivative, Forward Exchange Rate	1.21		1.21		1.21
Derivative, Notional Amount						86,000
Maturing in 2016 [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Notional Value Local Currency						$ 67,000
Derivative, Forward Exchange Rate	1.19		1.19		1.19