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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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The amount of revenue derived from managing real estate properties.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Segment Information (Operating Revenues by Geographic Reportable Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 13, 2020
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture	$ 97,287	$ 102,109
Operating revenues	76,254	75,433
Asset and property management fee income	(4,300)	(1,900)
Operating Segments
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture	97,660	101,323
Operating Segments \| New York
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture	41,105	38,696
Operating Segments \| San Francisco
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture	34,801	27,763
Operating Segments \| Washington, D.C.
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture	15,018	14,130
Operating Segments \| Boston
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture	4,149	3,674
Operating Segments \| All other office markets
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture	2,587	17,060
Corporate
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture	(373)	786
Eliminations
Segment Reporting Information [Line Items]
Operating revenues	29,273	28,545
Asset and property management fee income	(8,240)	(1,869)
Corporate Joint Venture
Segment Reporting Information [Line Items]
Asset and property management fee income	$ (2,153)	(1,869)
Corporate Joint Venture \| Terminal Warehouse
Segment Reporting Information [Line Items]
Economic interest	8.65%		8.65%
114 Fifth Avenue Joint Venture \| Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	49.50%
333 Market Street and University Circle \| Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	55.00%
Market Square Joint Venture \| Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	51.00%
Asset and property management fee income	$ (574)	(568)
1800 M Street Joint Venture \| Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	55.00%
Asset and property management fee income	$ (555)	$ (520)