Subsequent Events/Other (Details) (USD $)	1 Months Ended	6 Months Ended		12 Months Ended	18 Months Ended
	Aug. 02, 2012	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012	Mar. 31, 2011
Subsequent Events/Other (Textuals) [Abstract]
Land parcels acquired	1
Value Of Land Parcels Acquired Subsequent	$ 22,000,000
Number of Apartment Properties Sold Subsequent	4
Number of consolidated apartment units sold	1,062
Subsequent Event Sold Consolidated Property	95,695,000
Repayment of mortgage loans	16,842,617
Subsequent Event Stock Issued Shares	747,000
Subsequent Event Average Price Per Common Share Issued	$ 63.27
Subsequent Event Consideration For Shares Issued	47,300,000
additional shares available subsequent balance sheet date	6,347,004
Term Loan Principal Amount		500,000,000			500,000,000
Business Combination, Acquisition Related Costs		7,329,000	3,751,000
Noncash Project Abandonment Costs		3,565,000	3,038,000
Other Expenses		10,900,000	6,800,000
contracted aquisition price				1,325,000,000
contracted acquisition percent				26.50%
Remaining Percentage to be Contracted						26.50%
Remaining Acquisition Cost to be Contracted						1,580,000,000
BreakUpFee	150,000,000
Potential Business Combination Costs					6,200,000
Payments of Merger Related Costs, Financing Activities				2,600,000
Settlement Expense		4,200,000
Disposal Group Corporate Housing Business Sale			4,000,000
Seller Provided Financing			2,000,000
Proceeds Received From Seller Provided Finanacing		300,000			500,000
Discontinued Operation Corporate Housing Business Gain Loss On Disposal Of Discontinued Operation Net Of Tax					1,500,000
Estimates of lost revenue and garage reconstruction		22,800,000
Estimates Of Lost Revenue And Garage Reconstruction After Insurance Reimbursements		13,600,000
Initial insurance proceeds		3,467,109
Fees Related to Ownership Interest in Potential Transaction [Member]
Subsequent Events/Other (Textuals) [Abstract]
Potential Business Combination Costs		1,800,000			3,600,000
Lehman Fee [Member]
Subsequent Events/Other (Textuals) [Abstract]
BreakUpFee	70,000,000
BofA and Barclays Fee [Member]
Subsequent Events/Other (Textuals) [Abstract]
BreakUpFee	$ 80,000,000