Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Cash flows from operating activities:
Net income	$ 118,848	$ 13,310	$ 297,305	$ 8,101
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			226,935	259,161
Amortization of deferred loan costs and debt premiums			4,608	7,566
(Accretion) and amortization of above and below market lease intangibles, net			(17,244)	(29,847)
Stock-based compensation, net of capitalization			9,272	10,654
Equity in income of investments in real estate partnerships	(14,243)	(8,116)	(26,344)	(22,358)
Gain on sale of real estate, net of tax			(38,198)	(48,690)
Provision for impairment of real estate, net of tax	(20)		115	1,014
Goodwill impairment				132,128
Early extinguishment of debt		19,358		19,358
Distribution of earnings from investments in real estate partnerships			54,310	32,659
Settlement of derivative instruments			(2,472)
Deferred compensation expense			2,707	1,381
Realized and unrealized (gain) loss on investments			(3,177)	(1,427)
Changes in assets and liabilities:
Tenant and other receivables			(8,659)	4,072
Deferred leasing costs			(7,103)	(4,999)
Other assets			(6,932)	(7,670)
Accounts payable and other liabilities			25,879	20,223
Tenants’ security, escrow deposits and prepaid rent			(2,524)	(6,737)
Net cash provided by operating activities			508,478	374,589
Cash flows from investing activities:
Acquisition of operating real estate, net of cash acquired of $2,991 in 2021			(78,611)	(16,867)
Advance deposits refunded on acquisition of operating real estate			500	100
Real estate development and capital improvements			(120,827)	(149,293)
Proceeds from sale of real estate			131,861	125,539
Issuance of notes receivable			(20)	(551)
Investments in real estate partnerships			(21,788)	(47,957)
Return of capital from investments in real estate partnerships			86,449	23,235
Dividends on investment securities			125	193
Acquisition of investment securities			(22,422)	(10,580)
Proceeds from sale of investment securities			23,162	10,659
Net cash used in investing activities			(1,571)	(65,522)
Cash flows from financing activities:
Net proceeds from common stock issuance			82,510	125,608
Repurchase of common shares in conjunction with equity award plans			(4,066)	(5,512)
Proceeds from sale of treasury stock			96	269
Distributions to limited partners in consolidated partnerships, net			(3,272)	(2,193)
Distributions to exchangeable operating partnership unit holders			(1,363)	(1,366)
Dividends paid to common stockholders			(301,897)	(300,538)
Repayment of fixed rate unsecured notes				(300,000)
Proceeds from issuance of fixed rate unsecured notes, net				598,830
Proceeds from unsecured credit facilities				610,000
Repayment of unsecured credit facilities			(265,000)	(830,000)
Repayment of notes payable			(13,764)	(3,891)
Scheduled principal payments			(8,448)	(8,149)
Payment of loan costs			(7,468)	(5,063)
Early redemption costs				(21,748)
Net cash used in financing activities			(522,672)	(143,753)
Net (decrease) increase in cash and cash equivalents and restricted cash			(15,765)	165,314
Cash and cash equivalents and restricted cash at beginning of the period			378,450	115,562	$ 115,562
Cash and cash equivalents and restricted cash at end of the period	362,685	280,876	362,685	280,876	378,450
Supplemental disclosure of cash flow information:
Cash paid for interest (net of capitalized interest of $3,012 and $3,590 in 2021 and 2020, respectively)			113,647	121,307
Cash paid for income taxes, net of refunds			358	898
Supplemental disclosure of non-cash transactions:
Acquisition of real estate previously held within investments in real estate partnerships			(4,609)	5,986
Mortgage loans assumed by company with the acquisition of real estate			111,090	16,359
Mortgage loan assumed by purchaser with the sale of real estate				8,250
Common stock issued for partnership units exchanged			99
Real estate received in lieu of promote interest			13,589
Exchangeable operating partnership units issued for acquisition of real estate				1,275
Change in accrued capital expenditures			5,830	16,276
Common stock issued under dividend reinvestment plan	404	382	1,172	1,138
Stock-based compensation capitalized			600	650
Common stock and exchangeable operating partnership dividends declared but not paid			101,753
(Distributions to) contributions from limited partners in consolidated partnerships, net				(1,420)
Common stock issued for dividend reinvestment in trust			826	819
Contribution of stock awards into trust			1,416	1,439
Distribution of stock held in trust			966	442
Change in fair value of securities			334	288
Partnership Interest [Member]
Cash flows from operating activities:
Net income	118,848	13,310	297,305	8,101
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			226,935	259,161
Amortization of deferred loan costs and debt premiums			4,608	7,566
(Accretion) and amortization of above and below market lease intangibles, net			(17,244)	(29,847)
Stock-based compensation, net of capitalization			9,272	10,654
Equity in income of investments in real estate partnerships	(14,243)	(8,116)	(26,344)	(22,358)
Gain on sale of real estate, net of tax			(38,198)	(48,690)
Provision for impairment of real estate, net of tax	(20)		115	1,014
Goodwill impairment				132,128
Early extinguishment of debt		19,358		19,358
Distribution of earnings from investments in real estate partnerships			54,310	32,659
Settlement of derivative instruments			(2,472)
Deferred compensation expense			2,707	1,381
Realized and unrealized (gain) loss on investments			(3,177)	(1,427)
Changes in assets and liabilities:
Tenant and other receivables			(8,659)	4,072
Deferred leasing costs			(7,103)	(4,999)
Other assets			(6,932)	(7,670)
Accounts payable and other liabilities			25,879	20,223
Tenants’ security, escrow deposits and prepaid rent			(2,524)	(6,737)
Net cash provided by operating activities			508,478	374,589
Cash flows from investing activities:
Acquisition of operating real estate, net of cash acquired of $2,991 in 2021			(78,611)	(16,867)
Advance deposits refunded on acquisition of operating real estate			500	100
Real estate development and capital improvements			(120,827)	(149,293)
Proceeds from sale of real estate			131,861	125,539
Issuance of notes receivable			(20)	(551)
Investments in real estate partnerships			(21,788)	(47,957)
Return of capital from investments in real estate partnerships			86,449	23,235
Dividends on investment securities			125	193
Acquisition of investment securities			(22,422)	(10,580)
Proceeds from sale of investment securities			23,162	10,659
Net cash used in investing activities			(1,571)	(65,522)
Cash flows from financing activities:
Net proceeds from common stock issuance			82,510	125,608
Repurchase of common shares in conjunction with equity award plans			(4,066)	(5,512)
Proceeds from sale of treasury stock			96	269
Distributions to limited partners in consolidated partnerships, net			(3,272)	(2,193)
Dividends paid to common stockholders			(303,260)	(301,904)
Repayment of fixed rate unsecured notes				(300,000)
Proceeds from issuance of fixed rate unsecured notes, net				598,830
Proceeds from unsecured credit facilities				610,000
Repayment of unsecured credit facilities			(265,000)	(830,000)
Repayment of notes payable			(13,764)	(3,891)
Scheduled principal payments			(8,448)	(8,149)
Payment of loan costs			(7,468)	(5,063)
Early redemption costs				(21,748)
Net cash used in financing activities			(522,672)	(143,753)
Net (decrease) increase in cash and cash equivalents and restricted cash			(15,765)	165,314
Cash and cash equivalents and restricted cash at beginning of the period			378,450	115,562	115,562
Cash and cash equivalents and restricted cash at end of the period	$ 362,685	$ 280,876	362,685	280,876	$ 378,450
Supplemental disclosure of cash flow information:
Cash paid for interest (net of capitalized interest of $3,012 and $3,590 in 2021 and 2020, respectively)			113,647	121,307
Cash paid for income taxes, net of refunds			358	898
Supplemental disclosure of non-cash transactions:
Acquisition of real estate previously held within investments in real estate partnerships			(4,609)	5,986
Mortgage loans assumed by company with the acquisition of real estate			111,090	16,359
Mortgage loan assumed by purchaser with the sale of real estate				8,250
Common stock issued for partnership units exchanged			99
Real estate received in lieu of promote interest			13,589
Exchangeable operating partnership units issued for acquisition of real estate				1,275
Change in accrued capital expenditures			5,830	16,276
Common stock issued under dividend reinvestment plan			1,172	1,138
Stock-based compensation capitalized			600	650
Common stock and exchangeable operating partnership dividends declared but not paid			101,753
(Distributions to) contributions from limited partners in consolidated partnerships, net				(1,420)
Common stock issued for dividend reinvestment in trust			826	819
Contribution of stock awards into trust			1,416	1,439
Distribution of stock held in trust			966	442
Change in fair value of securities			$ 334	$ 288