Recent Transactions (Rental Properties Held for Sale) (Narrative) (Details)
|
3 Months Ended |
12 Months Ended |
|
Mar. 31, 2016
USD ($)
ft²
property
|
Dec. 31, 2015
USD ($)
property
|
| Real Estate Properties [Line Items] |
|
|
| Aggregate carrying value |
$ 36,110,000
|
|
| Mortgage loan |
767,573,000
|
$ 726,611,000
|
| Number of properties sold | property |
|
6
|
| Disposal Group, Held-for-sale, Not Discontinued Operations [Member] |
|
|
| Real Estate Properties [Line Items] |
|
|
| Assets held for sale, Deferred charges and other assets |
13,200,000
|
|
| Assets held for sale, Unbilled rents receivable, net |
20,100,000
|
|
| Assets held for sale, Accounts receivable, net of allowance |
1,300,000
|
|
| Assets held for sale, Accounts payable, accrued expenses and other liabilities |
3,400,000
|
|
| Assets held for sale, Rents received in advance and security deposits |
1,200,000
|
|
| Expected assets to be written off |
31,300,000
|
|
| Expected liabilities to be written off |
$ 796,000
|
|
| 1400L Street, NW in Washington, D.C. and 125 Broad Street in New York, New York [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member] |
|
|
| Real Estate Properties [Line Items] |
|
|
| Area of property (in square feet) | ft² |
683,000
|
|
| Number of properties held for sale | property |
2
|
|
| Estimated expected sales proceeds |
$ 272,000,000
|
|
| Expected disposition completion date |
second quarter of 2016
|
|