Discontinued Operations - Schedule of Cash Flows from Discontinued Operations (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019
1899 Pennsylvania Avenue [Member]
Statements of Cash Flows:
Cash provided by operating activities	[1]	$ 5,522
Proceeds from sale of real estate	[1],[2]	89,206
Total cash provided by investing activities	[1]	89,206
Cash used in financing activities	[1]	(96,896)
Additional Cash Flow Information:
Depreciation and amortization	[1]	$ 690
1899 Pennsylvania Avenue and Liberty Place [Member]
Statements of Cash Flows:
Cash provided by operating activities	[1]		$ 15,949
Proceeds from sale of real estate	[1],[2]		150,307
Additions to real estate	[1]		(1,514)
Total cash provided by investing activities	[1]		148,793
Cash used in financing activities	[1]		(162,294)
Additional Cash Flow Information:
Depreciation and amortization	[1]		$ 8,243

[1] Represents revenues, expenses, net income, and cash flow information of 1899 Pennsylvania Avenue in the year ended December 31, 2020 and 1899 Pennsylvania Avenue and Liberty Place in the year ended December 31, 2019

[2] Represents the proceeds from the sale of 1899 Pennsylvania Avenue in 2020 and Liberty Place in 2019.