Investments in Unconsolidated Real Estate Entities - Summary of Financial Information for Apartment LLCs (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Real Estate Properties [Line Items]
Real estate assets, net of accumulated depreciation of $57,913 and $54,936 at June 30, 2016 and December 31, 2015, respectively	$ 2,246,848	$ 2,203,193
Total assets	2,288,448	2,267,249
Total liabilities	1,080,816	1,017,089
Members' equity	1,200,272	1,243,027	$ 1,280,236	$ 1,285,960
Total liabilities, redeemable common units and equity	2,288,448	2,267,249
Unconsolidated Properties [Member]
Real Estate Properties [Line Items]
Real estate assets, net of accumulated depreciation of $57,913 and $54,936 at June 30, 2016 and December 31, 2015, respectively	207,708	208,345
Cash and other	6,693	5,995
Total assets	214,401	214,340
Mortgage notes payable	177,556	177,503
Other liabilities	4,302	2,994
Total liabilities	181,858	180,497
Members' equity	32,543	33,843
Total liabilities, redeemable common units and equity	214,401	214,340
Unconsolidated Properties [Member] | Apartment LLC [Member]
Real Estate Properties [Line Items]
Company's equity investment in Apartment LLCs	$ (12,196)	$ (12,017)