CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Cash flows from operating activities:
Net income	$ 142,234	$ 168,006
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	183,297	177,911
Amortization of deferred financing costs	1,837	1,882
Amortization of debt discount	642	411
Gain (Loss) on Extinguishment of Debt	122	(9,170)
Amortization of stock-based compensation	5,382	5,338
Equity in loss of, and return on, unconsolidated real estate entities and noncontrolling interests, net of eliminations	1,994	1,871
Abandonment of development pursuits	246	1,988
Unrealized Gain (Loss) on Derivatives	(2,654)	0	$ 2,894
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion	2,367	1,949
Gain (Loss) on Sale of Properties	(54,154)	(24,479)
Gain (Loss) on Sale of Other Investments	(131)	(4,903)
Increase (Decrease) in Prepaid Expense and Other Assets	9,423	(1,239)
Increase (Decrease) in Accrued Liabilities	39,784	3,799
Net Cash Provided by (Used in) Operating Activities, Total	330,145	341,704
Cash flows from investing activities:
Payments to Develop Real Estate Assets	(198,373)	(245,789)
Payments for Capital Improvements	(28,020)	(32,922)
Payments for Capital Improvements, Non Real Estate	(2,234)	(10,663)
Increase (Decrease) in Construction Payables	(8,655)	462
Proceeds from Sale of Real Estate Held-for-investment	76,543	63,073
Proceeds from Sale of Other Real Estate	13,569	98,790
Payments to Acquire Mortgage Notes Receivable	0	(179)
Proceeds from Sale and Collection of Notes Receivable	1,250	960
Payments to Acquire Businesses and Interest in Affiliates	(10,032)	(9,799)
Net Cash Provided by (Used in) Investing Activities, Total	(155,952)	(136,067)
Cash flows from financing activities:
Proceeds from Issuance of Common Stock	11	125
Payments of Ordinary Dividends	(222,734)	(213,671)
Proceeds from Unsecured Lines of Credit	0	750,000
Proceeds from Secured Notes Payable	0	51,000
Repayments of Notes Payable	(28,488)	(51,484)
Proceeds from Unsecured Notes Payable	0	699,252
Repayments of Unsecured Debt	0	(658,655)
Payments of Financing Costs	0	(5,988)
Payments for (Proceeds from) Hedge, Financing Activities	6,962	(20,314)
Proceeds from (Payments to) Noncontrolling Interests	(22)	(35)
Payment, Tax Withholding, Share-based Payment Arrangement	(13,228)	(14,346)
Payments of Capital Distribution	(12)	(12)
Payments of Distributions to Affiliates	(82)	(102)
Payment For Redemption Of Preferred Interest Obligation	(400)	(600)
Net Cash Provided by (Used in) Financing Activities, Total	(257,993)	535,170
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	(83,800)	740,807
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning Balance	313,532	127,614	127,614
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance	229,732	868,421	313,532
Cash paid during the period for interest, net of amount capitalized	37,252	36,985
Supplemental Cash Flow Information [Abstract]
Cash and cash equivalents				$ 129,298	$ 216,976	$ 777,995
Cash in escrow				100,434	96,556	90,426
Cash, cash equivalents and cash in escrow reported in the Condensed Consolidated Statements of Cash Flows	$ 229,732	$ 868,421	$ 127,614	$ 229,732	$ 313,532	$ 868,421