CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income	$ 697,327	$ 352,771	$ 423,562
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	442,682	560,215	243,680
Depreciation expense from discontinued operations	0	13,500	16,414
Amortization of deferred financing costs	6,383	6,803	6,427
Amortization of debt (premium) discount	(34,961)	(29,750)	0
Amortization of stock-based compensation	13,927	15,160	8,707
Equity in loss (income) of, and return on, unconsolidated entities and noncontrolling interests, net of eliminations	4,906	33,125	(12,103)
Cash flow hedge losses reclassified to earnings	6,237	59,376	1,889
Casualty and impairment loss	0	0	1,449
Abandonment of development pursuits	1,455	0	0
Loss on extinguishment of debt, net	412	14,921	1,781
Gain on sale of real estate assets	(255,300)	(278,471)	(146,591)
Gain on acquisition of unconsolidated entity	0	0	(14,194)
Decrease (increase) in cash in operating escrows	55	(28,960)	6,543
(Increase) decrease in resident security deposits, prepaid expenses and other assets	(3,441)	(5,372)	7,992
Decrease (increase) in accrued expenses, other liabilities and accrued interest payable	6,959	10,997	(4,737)
Net cash provided by operating activities	886,641	724,315	540,819
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(1,241,832)	(1,285,715)	(755,363)
Acquisition of real estate assets, including partnership interest	(47,000)	(839,469)	(155,755)
Capital expenditures—existing real estate assets	(46,902)	(24,415)	(23,452)
Capital expenditures—non-real estate assets	(5,923)	(2,200)	(3,076)
Proceeds from sale of communities, net of selling costs	297,466	919,682	274,018
Mortgage note receivable repayment	21,748	0	0
Increase in payables for construction	7,400	34,779	16,832
Decrease in cash in construction escrows	0	0	16,824
Distributions from unconsolidated real estate entities	203,945	42,955	26,700
Investments in unconsolidated real estate entities	(5,662)	(26,791)	(20,114)
Net cash used in investing activities	(816,760)	(1,181,174)	(623,386)
Cash flows from financing activities:
Issuance of common stock	346,134	4,703	2,430,190
Dividends paid	(593,643)	(526,050)	(365,572)
Issuance of mortgage notes payable	53,000	84,928	0
Repayments of mortgage notes payable, including prepayment penalties	(32,859)	(2,110,347)	(110,013)
Issuance of unsecured notes	550,000	750,000	700,000
Settlement of interest rate contract	0	(51,000)	(54,930)
Repayment of unsecured notes	(150,000)	(100,000)	(381,001)
Payment of deferred financing costs and issuance discounts	(7,820)	(10,100)	(15,664)
Redemption of units for cash by minority partners	0	(1,965)	0
Acquisition of joint venture partner equity interest	0	0	(3,350)
Distributions to DownREIT partnership unitholders	(26)	(32)	(29)
Distributions to joint venture and profit-sharing partners	(262)	(317)	(299)
Redemption of preferred interest obligation	(6,300)	(35,224)	0
Net cash provided by (used in) financing activities	158,224	(1,995,404)	2,199,332
Net increase (decrease) in cash and cash equivalents	228,105	(2,452,263)	2,116,765
Cash and cash equivalents, beginning of year	281,355	2,733,618	616,853
Cash and cash equivalents, end of year	509,460	281,355	2,733,618
Cash paid during the year for interest, net of amount capitalized	$ 191,966	$ 179,325	$ 119,268