Assets for Reportable Segment (Detail) - Parent Company [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 11,303,762	$ 11,323,781
Same Store [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	9,935,157	9,991,538
Non-Same Store and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,178,083	1,163,083
Corporate assets
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 190,522	$ 169,160