Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
REVENUES (NOTE 1)
Revenue	$ 201,202	$ 182,822
EXPENSES
Real estate taxes	18,639	17,146
Provision for bad debts (Note 1)	0	(265)
Ground leases (Notes 1 and 9)	1,972	1,561
General and administrative expenses	23,341	15,559
Leasing costs (Note 1)	1,757
Depreciation and amortization	66,135	62,715
Total expenses	149,993	128,387
OTHER (EXPENSES) INCOME
Interest income and other net investment gain (Note 10)	1,828	34
Interest expense (Note 3)	(11,243)	(13,498)
Total other (expenses) income	(9,415)	(13,464)
NET INCOME	41,794	40,971
Net income attributable to noncontrolling common units of the Operating Partnership	(700)	(751)
Net income attributable to noncontrolling interests in consolidated property partnerships	(4,191)	(3,974)
Total income attributable to noncontrolling interests	(4,891)	(4,725)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS (UNITHOLDERS)	$ 36,903	$ 36,246
Net income available to common stockholders per share – basic (in dollars per share)	$ 0.36	$ 0.36
Net income available to common stockholders per share – diluted (in dollars per share)	$ 0.36	$ 0.36
Weighted average common shares outstanding – basic (in shares)	100,901,390	98,744,220
Weighted average common shares outstanding – diluted (in shares)	101,443,179	99,213,610
Rental [Member]
REVENUES (NOTE 1)
Revenue	$ 199,382	$ 162,871
Tenant reimbursements [Member]
REVENUES (NOTE 1)
Revenue	0	19,150
Other property income [Member]
REVENUES (NOTE 1)
Revenue	1,820	801
Property [Member]
EXPENSES
Property expenses (Note 1)	$ 38,149	$ 31,671