Discontinued Operations - Schedule of Assets and Liabilities and Results of Operations Related to Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Balance Sheets:
Assets related to discontinued operations	$ 104,028		$ 104,836
Expenses:
Income from discontinued operations, net	1,521	$ 2,106
1899 Pennsylvania Avenue [Member]
Revenues:
Rental revenue	3,563
Fee and other income	99
Total revenues	3,662
Expenses:
Operating	1,451
Depreciation and amortization	690
Total expenses	2,141
Income from discontinued operations, net	1,521
1899 Pennsylvania Avenue [Member] | Discontinued Operations Held for Sale [Member]
Balance Sheets:
Real estate, net	93,837		94,251
Deferred rent receivable	4,121		4,206
Deferred charges, net	780		804
Intangible assets, net	5,290		5,575
Assets related to discontinued operations	$ 104,028		$ 104,836
1899 Pennsylvania Avenue and Liberty Place [Member]
Revenues:
Rental revenue		7,275
Fee and other income		128
Total revenues		7,403
Expenses:
Operating		2,920
Depreciation and amortization		2,377
Total expenses		5,297
Income from discontinued operations, net		$ 2,106