Assets for Reportable Segment (Detail) - Parent Company [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 6,827,921	$ 6,847,781
Large Market Same Store
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	3,733,104	3,768,455
Secondary Market Same Store
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,647,418	1,661,956
Non-Same Store and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,392,230	1,344,833
Corporate assets
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 55,169	$ 72,537