Significant Accounting Policies (Schedule Of Rental Property Improvements) (Details) - USD ($) $ in Thousands |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2019 |
Dec. 31, 2018 |
|
| Property, Plant and Equipment [Line Items] | ||
| Land held for development (including pre-development costs, if any) | $ 452,057 | $ 465,930 |
| Development and construction in progress, including land | 465,779 | 327,039 |
| Total | 917,836 | 792,969 |
| Buildings and improvement | 163,600 | 204,900 |
| Development [Member] | ||
| Property, Plant and Equipment [Line Items] | ||
| Land | $ 108,800 | $ 49,600 |