Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
OPERATING ACTIVITIES:
Net income (loss)	$ 48,175,000	$ 28,248,000
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	17,362,000	16,589,000
Depreciation and amortization, including amortization of debt issuance costs	49,360,000	49,936,000
Deferred rent	(6,614,000)	(9,341,000)
(Income) loss from unconsolidated real estate ventures, net	2,692,000	(3,601,000)
Amortization of market lease intangibles, net	(163,000)	(132,000)
Amortization of lease incentives	1,609,000	2,057,000
Loss on extinguishment of debt	33,000
Gain on sale of real estate	(59,477,000)	(39,033,000)
Net unrealized loss (gain) on derivative financial instruments not designated as cash flow hedges	(47,000)	48,000
Losses on operating lease receivables	2,718,000	1,568,000
Return on capital from unconsolidated real estate ventures	532,000	398,000
Other non-cash items	(116,000)	519,000
Changes in operating assets and liabilities:
Tenant and other receivables	(4,210,000)	(4,185,000)
Other assets, net	(1,105,000)	1,647,000
Accounts payable and accrued expenses	(5,968,000)	(18,943,000)
Other liabilities, net	(2,865,000)	(7,867,000)
Net cash provided by operating activities	41,916,000	17,908,000
INVESTING ACTIVITIES:
Development costs, construction in progress and real estate additions	(107,013,000)	(68,667,000)
Deposits for real estate acquisitions		(8,525,000)
Proceeds from sale of real estate	154,493,000	117,676,000
Distributions of capital from unconsolidated real estate ventures		6,555,000
Investments in unconsolidated real estate ventures	(3,563,000)	(2,851,000)
Net cash provided by investing activities	43,917,000	44,188,000
FINANCING ACTIVITIES:
Finance lease payments	(2,642,000)	(33,000)
Borrowings under mortgages payable	175,000,000
Borrowings under revolving credit facility	200,000,000
Repayments of mortgages payable	(2,221,000)	(3,065,000)
Repayments of revolving credit facility	(200,000,000)
Debt issuance costs	(9,278,000)
Common shares repurchased	(41,177,000)
Dividends paid to common shareholders	(30,184,000)	(39,298,000)
Distributions to redeemable noncontrolling interests	(3,828,000)	(5,895,000)
Contributions from noncontrolling interests		124,000
Net cash provided by (used in) financing activities	85,670,000	(48,167,000)
Net increase in cash and cash equivalents and restricted cash	171,503,000	13,929,000
Cash and cash equivalents and restricted cash as of the beginning of the period	142,516,000	399,532,000
Cash and cash equivalents and restricted cash as of the end of the period	314,019,000	413,461,000
SUPPLEMENTAL DISCLOSURE OF CASH FLOW AND NON-CASH INFORMATION:
Cash paid for interest (net of capitalized interest of $5,268 and $6,915 in 2020 and 2019)	10,927,000	15,489,000
Accrued capital expenditures included in accounts payable and accrued expenses	76,418,000	74,299,000
Write-off of fully depreciated assets	7,111,000	18,477,000
Conversion of common limited partnership units to common shares	31,126,000	57,001,000
Recognition (derecognition) of operating lease right-of-use assets	(13,151,000)	35,318,000
Recognition (derecognition) of liabilities related to operating lease right-of-use assets.	(13,151,000)	37,922,000
Recognition of finance lease right-of-use assets	42,354,000
Recognition of liabilities related to finance lease right-of-use assets	40,684,000
Cash paid for amounts included in the measurement of lease liabilities for operating leases	$ 1,396,000	$ 1,708,000