Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 517,582	$ 451,123	$ 447,080
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	224,444	219,857	209,050
Amortization of deferred financing costs	9,386	11,989	14,286
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	3,675	4,742	4,687
Non-cash lease expense	1,173	1,064
Compensation expense related to stock-based awards	16,281	13,051	11,176
Accrual of interest income added to principal of debt securities and notes receivable	(8,059)	0	0
Gain on real estate transactions	(18,075)	(1,205)	(30,807)
Distributions from unconsolidated real estate ventures in excess of earnings	6,893	6,358	6,867
Changes in operating assets and liabilities:
Other assets	(19,674)	(12,482)	(1,664)
Accounts payable and accrued expenses	17,974	15,522	2,736
Other liabilities	19,632	(2,333)	14,384
Net cash provided by operating activities	771,232	707,686	677,795
Cash flows from investing activities:
Acquisition of real estate assets	(320,148)	(349,494)	(426,388)
Development and redevelopment of real estate assets	(67,300)	(53,717)	(60,677)
Proceeds from sale of real estate assets	44,024	11,254	52,458
Investment in unconsolidated real estate entities	(64,792)	(197,759)	(65,500)
Return of investment in unconsolidated real estate ventures	371	3,982	49,130
Issuance and purchase of notes receivable	(313,355)	(185,993)	(13,850)
Investment in debt securities	(300,000)	0	0
Proceeds from sale of notes receivable	62,764	0	0
Principal payments received from notes receivable	10,102	157,861	25,226
Purchase of equipment and fixtures	(7,093)	(7,764)	(4,297)
Net cash used in investing activities	(955,427)	(621,630)	(443,898)
Cash flows from financing activities:
Proceeds from the sale of common stock, net of offering costs	103,468	198,827	90,231
Proceeds from notes payable and revolving lines of credit	3,281,000	2,214,000	1,413,030
Principal payments on notes payable and revolving lines of credit	(2,014,730)	(1,977,805)	(1,109,854)
Principal payments on notes payable to trusts	0	(30,928)	(88,662)
Deferred financing costs	(4,052)	(2,986)	(12,302)
Repurchase of exchangeable senior notes	(575,000)	0	(80,270)
Net proceeds from exercise of stock options	4,759	3,063	1,169
Repurchase of common stock	(67,873)	0	0
Proceeds from principal payments on note receivable collateralized by Preferred OP Units	16,213	0	0
Redemption of Operating Partnership units held by noncontrolling interests	(1,000)	0	(2,558)
Contributions from noncontrolling interests	66	173	122
Dividends paid on common stock	(467,765)	(458,114)	(424,907)
Distributions to noncontrolling interests	(33,615)	(34,243)	(33,250)
Net cash provided by (used in) financing activities	241,471	(88,013)	(247,251)
Net increase (decrease) in cash, cash equivalents, and restricted cash	57,276	(1,957)	(13,354)
Cash, cash equivalents, and restricted cash, beginning of the period	70,733	72,690	86,044
Cash, cash equivalents, and restricted cash, end of the period	128,009	70,733	72,690
Supplemental schedule of cash flow information
Interest paid	159,597	174,155	159,474
Income taxes paid	5,181	10,359	730
Redemption of Operating Partnership units held by noncontrolling interests for common stock
Noncontrolling interests in Operating Partnership	(4,005)	(13,057)	(1,337)
Common stock and paid-in capital	4,005	13,057	1,337
Establishment of operating lease right of use assets and lease liabilities
Real estate assets - operating lease right-of-use assets	8,014	277,557
Operating lease liabilities	(8,014)	(286,914)
Accounts payable and accrued expenses	0	9,357
Acquisitions of real estate assets
Real estate assets, net	(41,491)	21,066	88,842
Value of Operating Partnership units issued	0	0	(1,877)
Notes payable assumed	0	(17,157)	(87,500)
Investment in unconsolidated real estate ventures	0	(2,780)	535
Finance lease liability	41,491	0	0
Net liabilities assumed	0	(1,129)	0
Accrued construction costs and capital expenditures
Acquisition of real estate assets	656	2,203	778
Development and redevelopment of real estate assets	0	1,601	554
Accounts payable and accrued expenses	(656)	(3,804)	(1,332)
Contribution of Preferred OP Units to unconsolidated real estate venture
Investments in unconsolidated real estate ventures	0	(28,022)	0
Value of Preferred Operating Partnership units issued	0	28,022	0
Redemption of Preferred Operating Partnership units for common stock
Noncontrolling interests in Operating Partnership	(2,724)	0	0
Common stock and paid-in capital	2,724	0	0
Issuance of Preferred OP Units for additional investment in unconsolidated real estate venture
Conversion of Preferred Operating Units to Common Units	$ 0	$ 4,374	$ 6,851