Derivative Financial Instruments (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Expected increase to interest expense	$ 3,200,000		$ 3,200,000
Derivatives designated as cash flow hedges in accounts payable, accrued expenses and other liabilities [Abstract]
Interest rate swaps	1,103,000		1,103,000		9,369,000
Amount of unrealized gains/(losses) recognized in AOCL on derivatives (effective portion) [Abstract]
Interest rate swaps	6,319,000	(7,481,000)	6,599,000	(7,087,000)
Amount of (gains)/losses reclassified out of AOCL into contractual interest expense (effective portion) [Abstract]
Interest rate swaps	$ 800,000	$ 782,000	$ 1,588,000	$ 1,459,000