Investments in Unconsolidated Real Estate Ventures - Schedule of Equity in Earnings of Unconsolidated Real Estate Ventures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Equity in earnings	$ 12,895	$ 12,351	$ 10,541
VRS [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	2,919	4,041	3,510
PREXR {Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	(172)	0	0
SPI [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	2,380	1,951	1,541
PRISA [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	1,912	1,013	929
ESW II [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	174	145	102
Clarendon [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	620	581	551
ESSM [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	596	493	424
WCOT [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	614	569	498
ESS PRISA II LLC Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	1,016	793	764
ESW [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	2,269	1,875	1,571
ESNPS [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	823	633	513
Other Minority Owned Properties [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings	$ (256)	$ 257	$ 138