Derivative Financial Instruments - Effect of Derivative Financial Instruments on Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Not Designated as Hedging Instrument | Interest rate contracts | Other income
Derivative [Line Items]
Amount of Gain (Loss) Recognized Income on Derivative	$ (31)	$ 200	$ (12)	$ 266
Designated as Hedging Instrument | Cash Flow Hedging | Interest Expense
Derivative [Line Items]
Amount of Gain (Loss) Reclassified from Other Comprehensive Income into Income (Effective Portion)	(351)	(192)	(695)	(380)
Designated as Hedging Instrument | Interest rate contracts | Cash Flow Hedging
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivative (Effective Portion)	$ (1,292)	$ 1,501	$ (2,558)	$ 1,798