Subsequent Events (Details) (USD $)	3 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended		12 Months Ended		3 Months Ended		3 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Blackstone Portfolio [Member]	Jun. 30, 2012 Blackstone Portfolio [Member]	Dec. 31, 2012 Blackstone Portfolio [Member]	Jul. 18, 2012 Blackstone Portfolio [Member]	Sep. 30, 2012 Line of Credit [Member]	Jun. 30, 2012 Line of Credit Facility - Unsecured [Member] Line of Credit [Member]	Sep. 30, 2012 Term Loan - Unsecured [Member]	Jun. 30, 2012 Term Loan - Unsecured [Member] Unsecured Debt [Member]
Subsequent Event [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount											$ 100,000,000
Subsequent Event, Date				Jul. 18, 2012
Equity Method Investments							47,500,000
Equity Method Investment, Dividends or Distributions						10.50%
Proceeds from Sale of Property, Plant, and Equipment		39,200,000		321,000,000
Impairment of Real Estate	5,000,000		16,400,000		18,000,000
Repayments of Long-term Debt										150,000,000
Debt Instrument, Face Amount											250,000,000
Repayments of Lines of Credit								120,000,000
Line of Credit Facility, Maximum Borrowing Capacity									$ 600,000,000