CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Real estate:
Land	$ 3,310,543	$ 1,430,532
Buildings and improvements	11,249,812	7,112,763
Furniture, fixtures and equipment	325,288	254,378
Total Capitalized Cost	14,885,643	8,797,673
Less accumulated depreciation	(2,326,132)	(2,021,703)
Net operating real estate	12,559,511	6,775,970
Construction in progress, including land	1,146,805	802,857
Land held for development	409,930	316,037
Operating real estate assets held for sale, net		120,256
Total real estate, net	14,116,246	8,015,120
Cash and cash equivalents	111,147	2,733,618
Cash in escrow	94,400	50,033
Resident security deposits	27,886	24,748
Investments in unconsolidated real estate entities	365,521	129,352
Deferred financing costs, net	35,726	38,700
Deferred development costs	37,260	24,665
Prepaid expenses and other assets	183,999	143,842
Total assets	14,972,185	11,160,078
LIABILITIES AND EQUITY
Unsecured notes, net	1,846,113	1,945,798
Variable rate unsecured credit facility	142,000
Mortgage notes payable	3,865,206	1,905,235
Dividends payable	138,456	110,966
Payables for construction	84,984	53,677
Accrued expenses and other liabilities	224,189	223,651
Accrued interest payable	39,735	33,056
Resident security deposits	48,225	38,328
Liabilities related to real estate assets held for sale		1,547
Total liabilities	6,388,908	4,312,258
Redeemable noncontrolling interests	19,514	7,027
Equity:
Preferred stock, $0.01 par value; $25 liquidation preference; 50,000,000 shares authorized at both June 30, 2013 and December 31, 2012; zero shares issued and outstanding at June 30, 2013 and December 31, 2012, respectively
Common stock, $0.01 par value; 280,000,000 shares authorized at June 30, 2013 and 140,000,000 shares authorized at December 31, 2012; 129,398,867 and 114,403,472 shares issued and outstanding at June 30, 2013 and December 31, 2012, respectively	1,294	1,144
Additional paid-in capital	8,972,852	7,086,407
Accumulated earnings less dividends	(308,938)	(142,329)
Accumulated other comprehensive loss	(105,042)	(108,007)
Total equity	8,560,166	6,837,215
Noncontrolling interest	3,597	3,578
Total equity	8,563,763	6,840,793
Total liabilities and equity	$ 14,972,185	$ 11,160,078