Derivatives And Hedging (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Derivatives And Hedging [Line Items]
Accumulated loss from derivative instruments	$ (9,341,000)	$ (10,016,000)
Interest Rate Contracts [Member] | Cash Flow Hedges [Member]
Derivatives And Hedging [Line Items]
Number of active interest rate contracts held	3	3
Notional amount of interest rate cash flow hedge derivatives	26,900,000	27,100,000
Interest rate risk maturities through	September 2017	September 2017
Derivative, lower fixed interest rate range	2.30%	2.30%
Derivative, higher fixed interest rate range	5.00%	5.00%
Cash flow hedge gain (loss) to be amortized within 12 months	(2,900,000)
Interest Rate Contracts [Member] | Fair Value Hedges [Member]
Derivatives And Hedging [Line Items]
Number of active interest rate contracts held	4	4
Interest rate risk maturities through	October 2017	October 2017
Derivative, lower fixed interest rate range	4.20%	4.20%
Derivative, higher fixed interest rate range	7.50%	7.50%
Notional amount of interest rate fair value hedge derivatives	$ 119,000,000	$ 119,300,000
Derivative, lower variable interest rate range	0.50%	0.50%
Derivative, higher variable interest rate range	4.30%	4.30%