Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flow from operating activities:
Net income	$ 838,507	$ 218,065
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	142,956	140,566
Impairment charges	3,112	21,626
Equity award expense	11,482	10,284
Gain on sale of properties	(5,697)	(38,357)
Gain on marketable securities, net	(521,577)	(1,574)
Gain on sale of cost method investment	(190,832)	0
Distributions from joint ventures and other real estate investments	55,828	60,858
Change in accounts and notes receivable, net	(31,461)	2,159
Change in accounts payable and accrued expenses	(977)	(8,382)
Change in other operating assets and liabilities, net	(24,348)	(30,936)
Net cash flow provided by operating activities	237,447	313,529
Cash flow from investing activities:
Acquisition of operating real estate	(7,073)	0
Improvements to operating real estate	(110,826)	(139,865)
Improvements to real estate under development	(22,358)	(57,496)
Investments in marketable securities	0	(157)
Proceeds from sale of marketable securities	906	151
Proceeds from sale of cost method investment	227,521	0
Investments in and advances to real estate joint ventures	(8,006)	(16,214)
Reimbursements of investments in and advances to real estate joint ventures	1,737	2,702
Investments in and advances to other real estate investments	(1,278)	(9,685)
Reimbursements of investments in and advances to other real estate investments	0	5,960
Investment in other financing receivable	0	(48)
Collection of mortgage loans receivable	77	5,351
Proceeds from sale of operating properties	13,447	106,782
Proceeds from insurance casualty claims	2,450	2,000
Net cash flow provided by/(used for) investing activities	96,597	(100,519)
Cash flow from financing activities:
Principal payments on debt, excluding normal amortization of rental property debt	(88,426)	(6,198)
Principal payments on rental property debt	(5,440)	(6,179)
Proceeds from construction loan financing	0	7,149
(Repayments)/proceeds from the unsecured revolving credit facility, net	(200,000)	35,000
Proceeds from issuance of unsecured term loan	590,000	0
Repayments of unsecured term loan	(265,000)	0
Financing origination costs	(6,422)	(7)
Payment of early extinguishment of debt charges	0	(1,531)
Contributions from noncontrolling interests	109	0
Redemption/distribution of noncontrolling interests	(22,123)	(4,060)
Dividends paid	(254,716)	(265,226)
Proceeds from issuance of stock, net	981	1,811
Change in other financing liabilities	(5,267)	(3,359)
Net cash flow used for financing activities	(256,304)	(242,600)
Net change in cash and cash equivalents	77,740	(29,590)
Cash and cash equivalents, beginning of the period	123,947	143,581
Cash and cash equivalents, end of the period	201,687	113,991
Interest paid during the period including payment of early extinguishment of debt charges of $0 and $1,531, respectively (net of capitalized interest of $8,879 and $6,680, respectively)	91,502	86,621
Joint Ventures [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income	(23,806)	(41,287)
Other Real Estate Investments [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income	$ (15,740)	$ (19,493)