Commitments And Contingencies (Ground Lease Agreements) (Narrative) (Details) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Commitments And Contingencies [Abstract] | |||
| Ground lease expense incurred | $ 2,600,000 | $ 1,500,000 | $ 406,000 |