CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Real estate:
Land	$ 1,357,300	$ 1,330,329
Buildings and improvements	6,778,107	6,486,457
Furniture, fixtures and equipment	229,572	200,946
Total Capitalized Cost	8,364,979	8,017,732
Less accumulated depreciation	(1,863,466)	(1,659,770)
Net operating real estate	6,501,513	6,357,962
Construction in progress, including land	597,599	309,704
Land held for development	325,918	184,150
Operating real estate assets held for sale, net		103,829
Total real estate, net	7,425,030	6,955,645
Cash and cash equivalents	616,890	304,407
Cash in escrow	73,439	173,338
Resident security deposits	23,597	22,047
Investments in unconsolidated real estate entities	144,561	121,537
Deferred financing costs, net	33,761	33,024
Deferred development costs	24,770	77,253
Prepaid expenses and other assets	140,342	134,237
Total assets	8,482,390	7,821,488
LIABILITIES AND EQUITY
Unsecured notes, net	1,629,210	1,820,141
Variable rate unsecured credit facility
Mortgage notes payable	2,003,086	2,152,944
Dividends payable	84,953	76,676
Payables for construction	36,775	34,433
Accrued expenses and other liabilities	247,891	130,931
Accrued interest payable	34,262	31,845
Resident security deposits	37,258	33,569
Liabilities related to real estate assets held for sale		211,096
Total liabilities	4,073,435	4,491,635
Redeemable noncontrolling interests	7,063	14,262
Equity:
Preferred stock, $0.01 par value; $25 liquidation preference; 50,000,000 shares authorized at both December 31, 2011 and December 31, 2010; zero shares issued and outstanding at December 31, 2011 and December 31, 2010, respectively
Common stock, $0.01 par value; 140,000,000 shares authorized at both December 31, 2011 and December 31, 2010; 95,175,677 and 85,899,080 shares issued and outstanding at December 31, 2011 and December 31, 2010, respectively	952	859
Additional paid-in capital	4,652,457	3,593,677
Accumulated earnings less dividends	(171,648)	(282,743)
Accumulated other comprehensive loss	(87,020)	(1,175)
Total stockholders' equity	4,394,741	3,310,618
Noncontrolling interest	7,151	4,973
Total equity	4,401,892	3,315,591
Total liabilities and equity	$ 8,482,390	$ 7,821,488