Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
OPERATING ACTIVITIES:
Net income	$ 35,452,000	$ 45,619,000
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	47,432,000	39,690,000
Depreciation and amortization, including amortization of debt issuance costs	144,868,000	146,958,000
Deferred rent	(29,164,000)	(7,880,000)
Income from unconsolidated real estate ventures, net	(647,000)	(15,418,000)
Amortization of above- and below-market lease intangibles, net	(486,000)	(58,000)
Amortization of lease incentives	4,344,000	3,646,000
Reduction of gain on bargain purchase	0	(7,606,000)
Loss on extinguishment of debt	1,889,000	4,536,000
Gain on sale of real estate	(47,121,000)	(45,789,000)
Net unrealized loss (gain) on derivative financial instruments not designated as cash flow hedges	50,000	(1,264,000)
Losses on operating lease receivables	1,281,000	2,591,000
Return on capital from unconsolidated real estate ventures	1,836,000	6,820,000
Other non-cash items	20,000	1,499,000
Changes in operating assets and liabilities:
Tenant and other receivables	(9,077,000)	2,167,000
Other assets, net	(13,858,000)	(18,637,000)
Accounts payable and accrued expenses	(17,171,000)	(23,875,000)
Other liabilities, net	(7,009,000)	(11,550,000)
Net cash provided by operating activities	112,639,000	136,661,000
INVESTING ACTIVITIES:
Development costs, construction in progress and real estate additions	(294,355,000)	(260,396,000)
Deposits for real estate acquisitions	(9,125,000)	0
Proceeds from sale of real estate	157,810,000	346,149,000
Acquisition of interests in unconsolidated real estate ventures, net of cash acquired	0	(386,000)
Distributions of capital from unconsolidated real estate ventures	7,557,000	2,240,000
Proceeds from Sale of Equity Method Investments	0	24,602,000
Investments in and advances to unconsolidated real estate ventures	(7,325,000)	(22,663,000)
Other	0	(665,000)
Net cash (used in) provided by investing activities	(145,438,000)	88,881,000
FINANCING ACTIVITIES:
Acquisition of ownership interest in consolidated real estate venture	0	(548,000)
Finance lease payments	(103,000)	(82,000)
Borrowings under mortgages payable	0	43,823,000
Borrowings under revolving credit facility	0	35,000,000
Borrowings under unsecured term loans	0	250,000,000
Repayments of mortgages payable	(482,810,000)	(267,285,000)
Repayments of revolving credit facility	0	150,751,000
Debt issuance costs	515,000	372,000
Proceeds from the issuance of common stock, net of issuance costs	473,527,000	0
Dividends paid to common shareholders	(99,654,000)	(80,166,000)
Distributions to redeemable noncontrolling interests	(13,564,000)	(13,320,000)
Contributions from noncontrolling interests	125,000	250,000
Distributions to noncontrolling interests	(19,000)	(439,000)
Net cash used in financing activities	(123,013,000)	(183,890,000)
Net (decrease) increase in cash and cash equivalents and restricted cash	(155,812,000)	41,652,000
Cash and cash equivalents and restricted cash as of the beginning of the period	399,532,000	338,557,000
Cash and cash equivalents and restricted cash as of the end of the period	243,720,000	380,209,000
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AS OF END OF THE PERIOD:
Cash and cash equivalents and restricted cash	399,532,000	338,557,000
SUPPLEMENTAL DISCLOSURE OF CASH FLOW AND NON-CASH INFORMATION:
Cash paid for interest (net of capitalized interest of $23,211 and $14,863 in 2019 and 2018)	38,563,000	48,835,000
Accrued capital expenditures included in accounts payable and accrued expenses	99,876,000	78,910,000
Write-off of fully depreciated assets	49,319,000	23,049,000
Deconsolidation of 1900 N Street	0	95,923,000
Fair value of OP Unit redemptions	(57,318,000)	(109,208,000)
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	35,318,000	0
Lease liabilities related to operating right-of-use assets (1)	37,922,000	0
Cash paid for amounts included in the measurement of lease liabilities for operating leases	$ 4,629,000	$ 0