Derivative Financial Instruments (Narrative) (Details) In Thousands, unless otherwise specified	12 Months Ended										12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2013 EUR (€)	Dec. 31, 2011 USD ($)	Dec. 31, 2014 Interest Rate Swap [Member] USD ($)	Dec. 31, 2014 Interest Rate Swap [Member] Designated as Hedging Instrument [Member] Cash Flow Hedging [Member] USD ($)	Dec. 31, 2014 Interest Rate Swap [Member] Not Designated as Hedging Instrument [Member] USD ($)	Dec. 31, 2013 Foreign Exchange Option [Member] USD ($)	Dec. 31, 2013 Foreign Exchange Option [Member] EUR (€)	Dec. 31, 2014 Foreign Exchange Option [Member] Other Income [Member] USD ($)
Derivative [Line Items]
Derivative, Notional Amount						$ 519,313	$ 319,313	$ 200,000		€ 125,000
Cash and cash equivalents	201,367	521,951	610,970	250,000	215,836
Prepaid Expense and Other Assets, Current	74,294	65,512							2,577
Unrealized Gain (Loss) on Derivatives	$ 1,780	$ 4,313	$ (8,739)								$ 1,754