Derivative Financial Instruments - Effect of Derivative Financial Instruments on Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Not Designated as Hedging Instrument | Interest rate contracts | Other Income
Derivative [Line Items]
Amount of Gain (Loss) Recognized Income on Derivative	$ (16)	$ (70)	$ 249	$ (125)
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)	(207)		(587)
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate contracts
Derivative [Line Items]
Amount of Gain Recognized in Other Comprehensive Income on Derivative (Effective Portion)	$ (248)	$ (376)	$ 1,550	$ (1,529)