Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flow from operating activities:
Net income	$ 801,078	$ 303,518
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	214,660	209,440
Impairment charges	3,509	41,235
Early extinguishment of debt charges	7,538	0
Equity award expense	18,203	15,025
Gain on sale of properties	(5,697)	(47,382)
Gain on marketable securities, net	(444,646)	(1,375)
Gain on sale of cost method investment	(190,832)	0
Distributions from joint ventures and other real estate investments	135,791	78,940
Change in accounts and notes receivable, net	(21,175)	(6,908)
Change in accounts payable and accrued expenses	42,064	29,515
Change in other operating assets and liabilities, net	(32,617)	(57,831)
Net cash flow provided by operating activities	465,942	482,459
Cash flow from investing activities:
Acquisition of operating real estate	(7,073)	0
Improvements to operating real estate	(164,366)	(228,029)
Improvements to real estate under development	(22,358)	(85,609)
Investments in marketable securities	0	(244)
Proceeds from sale of marketable securities	931	1,920
Proceeds from sale of cost method investment	227,325	0
Investments in and advances to real estate joint ventures	(14,640)	(22,129)
Reimbursements of investments in and advances to real estate joint ventures	4,400	10,274
Investments in and advances to other real estate investments	(4,918)	(12,503)
Reimbursements of investments in and advances to other real estate investments	297	5,960
Investment in other financing receivable	0	(48)
Collection of mortgage loans receivable	114	5,402
Investment in other investments	(500)	(2,500)
Proceeds from sale of properties	21,718	163,199
Proceeds from insurance casualty claims	2,450	3,000
Net cash flow provided by/(used for) investing activities	43,380	(161,307)
Cash flow from financing activities:
Principal payments on debt, excluding normal amortization of rental property debt	(158,556)	(6,198)
Principal payments on rental property debt	(8,036)	(9,265)
Proceeds from construction loan financing	0	8,752
(Repayments)/proceeds from the unsecured revolving credit facility, net	(200,000)	100,000
Financing origination costs	(17,851)	(7,448)
Payment of early extinguishment of debt charges	(7,538)	(1,531)
Contributions from noncontrolling interests	109	0
Redemption/distribution of noncontrolling interests	(22,483)	(6,489)
Dividends paid	(304,320)	(401,280)
Proceeds from issuance of stock, net	981	3,351
Redemption of preferred stock	0	(350,000)
Change in other financing liabilities	(5,693)	(3,315)
Net cash flow used for financing activities	(308,292)	(323,423)
Net change in cash and cash equivalents	201,030	(2,271)
Cash and cash equivalents, beginning of the period	123,947	143,581
Cash and cash equivalents, end of the period	324,977	141,310
Interest paid during the period including payment of early extinguishment of debt charges of $7,538 and $1,531, respectively (net of capitalized interest of $11,283 and $10,874, respectively)	128,591	111,224
Senior Unsecured Notes [Member]
Cash flow from financing activities:
Proceeds from issuance of unsecured debt	900,000	350,000
The 3.20% Senior Unsecured Note [Member]
Cash flow from financing activities:
Repayments of unsecured debt	(484,905)	0
Term Loan [Member]
Cash flow from financing activities:
Proceeds from issuance of unsecured debt	590,000	0
Repayments of unsecured debt	(590,000)	0
Joint Ventures [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income	(35,039)	(58,960)
Other Real Estate Investments [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income	$ (26,895)	$ (22,758)