Assets for Reportable Segment (Detail) - Parent Company [Member] - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 6,881,313	$ 6,847,781
Large Market Same Store
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	3,653,852	3,768,455
Secondary Market Same Store
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,570,150	1,661,956
Non-Same Store and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,598,139	1,344,833
Corporate assets
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 59,172	$ 72,537