Derivative Financial Instruments (Schedule of Interest Rate Swap Agreements Impact on Other Comprehensive Income) (Details) (Interest Expense, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest Expense
Derivative [Line Items]
Gain(Loss) Recognized in OCI - Effective Portion	$ (2,082)	$ 1,481	$ (6,220)
Gain(Loss) Reclassified from AOCI into Income - Effective Portion	$ (3,606)	$ (2,809)	$ (1,340)