Disclosure Of Fair Value Of Assets And Liabilities (Narrative) (Details)
|
12 Months Ended |
|
Dec. 31, 2017
USD ($)
property
|
Dec. 31, 2016
USD ($)
property
|
| Fair Value Inputs, Assets, Quantitative Information [Line Items] |
|
|
| Fair value of Company's long-term debt |
$ 2,764,033,000
|
$ 2,308,488,000
|
| Principal balance outstanding |
$ 2,809,568,000
|
$ 2,340,009,000
|
| Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member] |
|
|
| Fair Value Inputs, Assets, Quantitative Information [Line Items] |
|
|
| Number of properties held for sale | property |
|
8
|
| Aggregate carrying value |
|
$ 39,700,000
|
| Estimated expected sales proceeds |
|
49,000,000
|
| Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member] | Parsippany, Paramus, Rochelle Park, Hamilton And Wall, New Jersey And White Plains, New York [Member] |
|
|
| Fair Value Inputs, Assets, Quantitative Information [Line Items] |
|
|
| Number of properties held for sale | property |
21
|
|
| Aggregate carrying value |
$ 171,600,000
|
|
| Estimated expected sales proceeds |
223,000,000
|
|
| Disposal Group, Not Discontinued Operations [Member] |
|
|
| Fair Value Inputs, Assets, Quantitative Information [Line Items] |
|
|
| Sales proceeds |
399,332,000
|
664,481,000
|
| Unrealized losses on rental properties held for sale |
$ (12,331,000)
|
$ (7,665,000)
|