Derivative Financial Instruments (Gains (losses) recognized on derivatives (cash flow hedges)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Interest Expense | Interest Rate Swap 1
Trading Activity, Gains and Losses, Net [Line Items]
Effective Portion, Recognized in OCI, Amount of Gain (Loss)	$ 66	$ 22
Effective Portion, Reclassified from AOCI into Income, Amount of Gain (Loss)	(71)	(75)
Interest Expense | Interest Rate Swap 2
Trading Activity, Gains and Losses, Net [Line Items]
Effective Portion, Recognized in OCI, Amount of Gain (Loss)	143	29
Effective Portion, Reclassified from AOCI into Income, Amount of Gain (Loss)	(142)	(128)
Interest Expense | Interest Rate Swap 3
Trading Activity, Gains and Losses, Net [Line Items]
Effective Portion, Recognized in OCI, Amount of Gain (Loss)	131	88
Effective Portion, Reclassified from AOCI into Income, Amount of Gain (Loss)	(142)	(136)
Interest Expense | Interest Rate Swap 4
Trading Activity, Gains and Losses, Net [Line Items]
Effective Portion, Recognized in OCI, Amount of Gain (Loss)	247	282
Effective Portion, Reclassified from AOCI into Income, Amount of Gain (Loss)	(150)	(155)
Other Income | Interest Rate Swap 1
Trading Activity, Gains and Losses, Net [Line Items]
Ineffective Portion, Recognized in Income on Derivatives, Amount of Gain (Loss)	0	0
Other Income | Interest Rate Swap 2
Trading Activity, Gains and Losses, Net [Line Items]
Ineffective Portion, Recognized in Income on Derivatives, Amount of Gain (Loss)	0	0
Other Income | Interest Rate Swap 3
Trading Activity, Gains and Losses, Net [Line Items]
Ineffective Portion, Recognized in Income on Derivatives, Amount of Gain (Loss)	0	0
Other Income | Interest Rate Swap 4
Trading Activity, Gains and Losses, Net [Line Items]
Ineffective Portion, Recognized in Income on Derivatives, Amount of Gain (Loss)	$ 0	$ 0