CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Real estate:
Land	$ 1,440,590	$ 1,312,538
Buildings and improvements	7,185,853	6,574,297
Furniture, fixtures and equipment	255,733	223,161
Total Capitalized Cost	8,882,176	8,109,996
Less accumulated depreciation	(2,034,364)	(1,780,309)
Net operating real estate	6,847,812	6,329,687
Construction in progress, including land	802,883	597,303
Land held for development	316,037	325,918
Operating real estate assets held for sale, net	48,388	172,122
Total real estate, net	8,015,120	7,425,030
Cash and cash equivalents	2,733,618	616,853
Cash in escrow	50,033	73,400
Resident security deposits	24,748	23,597
Investments in unconsolidated real estate entities	129,352	144,561
Deferred financing costs, net	38,700	33,653
Deferred development costs	24,665	24,770
Prepaid expenses and other assets	143,842	140,526
Total assets	11,160,078	8,482,390
LIABILITIES AND EQUITY
Unsecured notes, net	1,945,798	1,629,210
Variable rate unsecured credit facility	0
Mortgage notes payable	1,905,235	1,969,986
Dividends payable	110,966	84,953
Payables for construction	53,677	36,845
Accrued expenses and other liabilities	224,194	245,520
Accrued interest payable	33,056	34,210
Resident security deposits	38,626	35,968
Liabilities related to real estate assets held for sale	706	36,743
Total liabilities	4,312,258	4,073,435
Redeemable noncontrolling interests	7,027	7,063
Equity:
Preferred stock, $0.01 par value; $25 liquidation preference; 50,000,000 shares authorized at both December 31, 2012 and December 31, 2011; zero shares issued and outstanding at December 31, 2012 and December 31, 2011, respectively
Common stock, $0.01 par value; 140,000,000 shares authorized at both December 31, 2012 and December 31, 2011; 114,403,472 and 95,175,677 shares issued and outstanding at December 31, 2012 and December 31, 2011, respectively	1,144	952
Additional paid-in capital	7,086,407	4,652,457
Accumulated earnings less dividends	(142,329)	(171,648)
Accumulated other comprehensive loss	(108,007)	(87,020)
Total equity	6,837,215	4,394,741
Noncontrolling interest	3,578	7,151
Total equity	6,840,793	4,401,892
Total liabilities and equity	$ 11,160,078	$ 8,482,390