Real Estate - Variable Interest Entities (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
Real Estate Properties [Line Items]
Land		$ 573,315	$ 573,315
Accounts payable and other liabilities		50,684	46,967
Tenant security deposits		$ 9,002	8,802
Six Fifty North Glebe Road [Member]
Real Estate Properties [Line Items]
Variable interest entity, qualitative or quantitative information, ownership percentage		90.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		10.00%
Land		$ 12,851	12,851
Income producing property		37,954	37,949
Accumulated depreciation and amortization		(5,127)	(4,571)
Other assets		622	456
Real Estate Investments, Joint Ventures		46,300	46,685
Mortgage notes payable (1)	[1]	31,798	31,869
Accounts payable and other liabilities		326	186
Tenant security deposits		98	99
Accounts payable and accrued liabilities related to joint ventures		$ 32,222	$ 32,154

[1] The mortgage notes payable balances as of March 31, 2017 and December 31, 2016 are eliminated in consolidation due to the purchase of the loan by Washington REIT in January 2016.