Segments - Schedule of Reconciliation of NOI to Net Loss Attributable to Common Stockholders (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
NOI	[1]	$ 117,066	$ 114,849	$ 357,823	$ 354,213
Fee income		6,561	9,153	19,432	21,692
Depreciation and amortization expense		(57,522)	(58,889)	(175,752)	(176,032)
General and administrative expenses		(13,257)	(16,805)	(46,039)	(46,955)
NOI from unconsolidated joint ventures		(16,214)	(12,935)	(37,097)	(36,703)
Income (loss) from unconsolidated joint ventures		223	(4,268)	(20,810)	(14,444)
Interest and other income, net		138	1,104	2,510	2,360
Interest and debt expense		(36,266)	(35,792)	(105,919)	(108,420)
Adjustments related to discontinued operations			(2,157)		(6,515)
Other, net		189	(137)	101	(457)
Income (loss) from continuing operations, before income taxes		5,505	(5,877)	(1,164)	(11,261)
Income tax expense		(873)	(393)	(2,448)	(1,135)
Income (loss) from continuing operations, net		4,632	(6,270)	(3,612)	(12,396)
Income from discontinued operations, net			2,147		5,815
Net income (loss)		4,632	(4,123)	(3,612)	(6,581)
Consolidated joint ventures		(3,768)	(3,566)	(16,924)	(5,485)
Consolidated real estate fund		(3,123)	79	(3,179)	1,291
Operating Partnership		204	652	2,139	895
Net loss attributable to common stockholders		(2,055)	(6,958)	(21,576)	(9,880)
One Steuart Lane [Member]
Segment Reporting Information [Line Items]
Income (loss) from unconsolidated joint ventures		3,363	$ (223)	3,138	$ (1,773)
NOI attributable to unconsolidated joint ventures		$ 4,587		$ 4,587

[1] NOI is used to measure the operating performance of our properties. NOI consists of rental revenue (which includes property rentals, tenant reimbursements and lease termination income) and certain other property-related revenue less operating expenses (which includes property-related expenses such as cleaning, security, repairs and maintenance, utilities, property administration and real estate taxes). We use NOI internally as a performance measure and believe it provides useful information to investors regarding our financial condition and results of operations because it reflects only those income and expense items that are incurred at the property level. Other real estate companies may use different methodologies for calculating NOI and, accordingly, our presentation of NOI may not be comparable to other real estate companies.