Derivative Financial Instruments (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivative [Line Items]
Number of derivative instruments obtained	6
Term of derivative instruments (in years)	7
Amount of borrowings outstanding	$ 225,000,000
Interest rate under derivative instruments	1.678%
Expected increase to interest expense	2,400,000
Derivatives designated as cash flow hedges in other liabilities [Abstract]
Interest rate swaps	2,202,000	0
Amount of unrealized gain/(loss) recognized in AOCL on derivatives (effective portion) [Abstract]
Interest rate swaps	(2,202,000)	0	937,000
Amount of (gain)/loss reclassified out of AOCL into contractual interest expense (effective portion) [Abstract]
Interest rate swaps	$ (118,000)	$ 237,000	$ (249,000)