Indebtedness (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Mortgage loans paid off and retired prior to maturity
Loan Principal Paid Off	$ 62,662
Loss on Early Retirement of Debt	(2,128)
Maturity Date September 1, 2012 [Member]
Mortgage loans paid off and retired prior to maturity
Loan Principal Paid Off	14,520
Interest Rate	6.75%
Payoff Date	Feb. 10, 2011
Maturity Date	Sep. 01, 2012
Loss on Early Retirement of Debt	(213)
Maturity Date December 1, 2014 [Member]
Mortgage loans paid off and retired prior to maturity
Loan Principal Paid Off	18,662
Interest Rate	7.50%
Payoff Date	Mar. 20, 2011
Maturity Date	Dec. 01, 2014
Loss on Early Retirement of Debt	(813)
Maturity Date October 1, 2014 [Member]
Mortgage loans paid off and retired prior to maturity
Loan Principal Paid Off	27,389
Interest Rate	7.50%
Payoff Date	Apr. 01, 2011
Maturity Date	Oct. 01, 2014
Loss on Early Retirement of Debt	(1,104)
Maturity Date January 1, 2012 [Member]
Mortgage loans paid off and retired prior to maturity
Loan Principal Paid Off	2,091
Interest Rate	7.54%
Payoff Date	Nov. 30, 2011
Maturity Date	Jan. 01, 2012
Loss on Early Retirement of Debt	$ 2