Summary of Investments in Real Estate (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014 Property		Dec. 31, 2013 Property
Real Estate Properties [Line Items]
Number of Properties	80		62
Investments in real estate, Book Value	$ 1,556,530		$ 1,131,931
Accumulated depreciation and amortization	155,815	[1]	127,745	[1]
Independence Realty Trust Inc
Real Estate Properties [Line Items]
Number of Properties	22		10
Number of units	6,470		2,790
Investments in real estate, Book Value	444,050		190,096
Accumulated depreciation and amortization	$ 20,848		$ 15,775

[1] As of September 30, 2014, includes 22 apartment properties owned by Independence Realty Trust, Inc., with 6,470 units and a book value of $444,050 and accumulated depreciation of $20,848. As of December 31, 2013, includes 10 apartment properties owned by Independence Realty Trust, Inc., with 2,790 units and a book value of $190,096 and accumulated depreciation of $15,775.