Debt (Details) (USD $) In Thousands, unless otherwise specified				6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended
	Jun. 30, 2012	May 14, 2012	Dec. 31, 2011	Jun. 30, 2012 Five Point Six Five Percent Loans Due October Two Thousand And Thirteen [Member]	Dec. 31, 2011 Five Point Six Five Percent Loans Due October Two Thousand And Thirteen [Member]	Jun. 30, 2012 Two Point Seven Seven Percent Loans Due October Two Thousand And Fourteen [Member]	Dec. 31, 2011 Two Point Seven Seven Percent Loans Due October Two Thousand And Fourteen [Member]	Jun. 30, 2012 Five Point Five Percent Loans Due April Two Thousand And Fifteen [Member]	Dec. 31, 2011 Five Point Five Percent Loans Due April Two Thousand And Fifteen [Member]	Jun. 30, 2012 Five Point Eight Two Percent Loan Due April Two Thousand Fifteen [Member]	Dec. 31, 2011 Five Point Eight Two Percent Loan Due April Two Thousand Fifteen [Member]	Jun. 30, 2012 Five Point Seven Five Percent Loan Due March Two Thousand Sixteen [Member]	Dec. 31, 2011 Five Point Seven Five Percent Loan Due March Two Thousand Sixteen [Member]	Jun. 30, 2012 Six Point Two One Percent Due April Two Thousand Sixteen [Member]	Dec. 31, 2011 Six Point Two One Percent Due April Two Thousand Sixteen [Member]	Jun. 30, 2012 Three Point Five Percent Due May Two Thousand Sixteen [Member]	Dec. 31, 2011 Three Point Five Percent Due May Two Thousand Sixteen [Member]	Jun. 30, 2012 Five Point Five Five Percent Loans Due March Two Thousand Seventeen [Member]	Dec. 31, 2011 Five Point Five Five Percent Loans Due March Two Thousand Seventeen [Member]	Jun. 30, 2012 Six Point Four Zero Percent Loans Due July Two Thousand Seventeen [Member]	Dec. 31, 2011 Six Point Four Zero Percent Loans Due July Two Thousand Seventeen [Member]	Jun. 30, 2012 Six Point Four Eight Percent Loans Due April Two Thousand Eighteen [Member]	Dec. 31, 2011 Six Point Four Eight Percent Loans Due April Two Thousand Eighteen [Member]
Mortgage Loans Payable
Debt Instrument, Maturity Date, Description				Oct 2013		Oct 2014		Apr 2015		Apr 2015		Mar 2016		Apr 2016		May 2016		Mar 2017		Jul 2017		Apr 2018
Interest rate in condition 2		10.00%				2.50%										2.50%
Interest Rate				5.65%		2.77%		5.50%		5.82%		5.75%		6.21%		3.50%		5.55%		6.40%		6.48%
Mortgage loans payable	$ 229,891		$ 230,940	$ 15,457	$ 15,682	$ 21,000	$ 21,000	$ 8,700	$ 8,900	$ 4,129	$ 4,169	$ 20,360	$ 20,522	$ 54,301	$ 56,423	$ 51,636	$ 49,585	$ 5,577	$ 5,600	$ 37,861	$ 38,132	$ 10,870	$ 10,927