Assets for Reportable Segment (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 3,028,257	$ 2,751,068
Large Market Same Store
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,265,355	1,108,827
Secondary Market Same Store
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	806,170	654,315
Non-Same Store and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	674,432	949,398
Corporate assets
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 282,300	$ 38,528