Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flow from operating activities:
Net income	$ 142,154	$ 312,739
Adjustments to reconcile net income to net cash provided by operating activities: by operating activities:
Depreciation and amortization	84,856	74,569
Asset Impairment Charges	5,840	6,473
Equity award expense	7,877	8,394
Gain on sale of operating properties	$ (30,883)	(32,055)
Gain on change in control of interests, net		(139,801)
Equity in income of joint ventures, net	$ (69,933)	(97,550)
Equity in income from other real estate investments, net	(10,799)	(14,369)
Distributions from joint ventures and other real estate investments	26,730	40,110
Change in accounts and notes receivable	1,247	(5,981)
Change in accounts payable and accrued expenses	8,869	11,985
Change in other operating assets and liabilities	(29,002)	(1,424)
Net cash flow provided by operating activities	136,956	163,090
Cash flow from investing activities:
Acquisition of operating real estate and other related net assets	(11,436)	(537,223)
Improvements to operating real estate	(32,866)	$ (29,888)
Acquisition of real estate under development	(12,895)
Improvements to real estate under development	(5,333)	$ (2,021)
Proceeds from sale/repayments of marketable securities	1,850	700
Investments and advances to real estate joint ventures	(17,505)	(29,720)
Reimbursements of investments and advances to real estate joint ventures	28,327	7,599
Distributions from liquidation of real estate joint ventures	50,902	53,450
Return on investment from liquidation of real estate joint ventures	40,000	20,889
Investment in other real estate investments	(190)	(239)
Reimbursements of investments and advances to other real estate investments	2,921	17,946
Collection of mortgage loans receivable	$ 231	292
Investment in other investments		(190,278)
Proceeds from sale of operating properties	$ 79,245	$ 81,037
Proceeds from sale of development properties	4,551
Net cash flow used for/(provided by) investing activities	127,802	$ (607,456)
Cash flow from financing activities:
Principal payments on debt, excluding normal amortization of rental property debt	(101,205)	(49,286)
Principal payments on rental property debt	(5,971)	(7,155)
Proceeds under the unsecured revolving credit facility, net	$ 180,000	40,000
Proceeds from issuance of unsecured term loan/notes		1,000,000
Repayments under unsecured term loan/notes	$ (300,000)	(500,000)
Financing origination costs	(91)	(9,161)
Change in tenants' security deposits	$ 594	1,267
Contributions from noncontrolling interests		105,498
Dividends paid	$ (117,030)	(113,400)
Proceeds from issuance of stock	111,411	10,258
Net cash flow (used for)/provided by financing activities	(232,292)	478,021
Change in cash and cash equivalents	32,466	33,655
Cash and cash equivalents, beginning of period	189,534	187,322
Cash and cash equivalents, end of period	222,000	220,977
Interest paid during the period (net of capitalized interest of $1,699, and $1,134, respectively)	39,508	37,564
Income taxes paid during the period	$ 23,960	$ 4,055