Accounting for Derivatives (Details 3) (Derivatives designated as cash flow hedges, Interest rate hedges, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Effect of derivative instruments on results of operations
Gain (Loss) Recognized in Other Comprehensive Income (Loss) on Derivatives	$ (6,253)	$ (955)
Interest Expense
Effect of derivative instruments on results of operations
Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss)	$ (1,525)	$ (1,000)