Subsequent Events - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	0 Months Ended		1 Months Ended
	Mar. 31, 2015 Communities	Apr. 29, 2015 Communities apartmentunits	Apr. 01, 2015 Communities apartmentunits	Apr. 29, 2015 Communities apartmentunits
Subsequent Event [Line Items]
Number Of Properties Sold	1
Number of Units in Real Estate Property	81,976
Subsequent Event [Member]
Subsequent Event [Line Items]
Number Of Properties Sold		10	4	14
Number of Units in Real Estate Property		2,110	640	2,110
Gain on sale of depreciable real estate assets excluded from discontinued operations				$ 105,000
Westbury Creek [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property			120
Bradford Pointe [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property			192
Woodwinds [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property			144
Colony At South Park [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property			184
Huntington Chase [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property		200		200
Southland Station [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property		304		304
Sutton Place [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property		253		253
Oaks [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property		100		100
Bradford Chase [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property		148		148
Woods of Post House [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property		122		122
Post House North [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property		145		145
Post House Jackson [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property		150		150
Anatole [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property		208		208
Paddock Park Ocala [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property		480		480