Subsequent Events (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Apr. 28, 2016 USD ($) buildings unit Contracts	Mar. 31, 2016 USD ($) apartment	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Subsequent Event [Line Items]
Disposal Group, Not Discontinued Operation, Sale Price		$ 137,100
Number of Units in Real Estate Property | apartment		506
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations [Member] | Maryland Portfolio [Member]
Subsequent Event [Line Items]
Land		$ 26,380		$ 26,380
Income producing property		215,300		215,108
Accumulated depreciation and amortization		(121,686)		(119,381)
Other assets		12,885		12,930
Total assets		132,879		135,037
Accounts payable and other liabilities		1,255		1,339
Advance rents		1,715		1,774
Tenant security deposits		1,761		1,791
Total liabilities		4,731		$ 4,904
Real estate rental revenue		8,430	$ 7,594
Net income		$ 2,726	$ 1,718
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations [Member] | Maryland Portfolio [Member] | Subsequent Event
Subsequent Event [Line Items]
Number of Purchase and Sale Agreements | Contracts	2
number of buildings held for sale | buildings	6
Proceeds from Sale of Property Held-for-sale	$ 10,000
Disposal Group, Not Discontinued Operation, Sale Price	$ 240,000
Multifamily [Member] | Subsequent Event
Subsequent Event [Line Items]
Number of Units in Real Estate Property | unit	1,222
Purchase and sale agreement, purchase price	$ 244,800
Change in Escrow Deposit To Non-refundable, Related to Property Acquisition	$ 12,500