Recent Transactions (Unconsolidated Joint Venture Activity) (Narrative) (Details) - USD ($) |
3 Months Ended | 9 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|---|
Sep. 01, 2021 |
Apr. 29, 2021 |
Sep. 30, 2021 |
Sep. 30, 2021 |
Dec. 31, 2020 |
|
| Real Estate Properties [Line Items] | |||||
| Gain on sale from unconsolidated joint ventures | $ (1,886,000) | $ (1,886,000) | |||
| Crystal House [Member] | Unconsolidated Joint Venture Multi-Family Properties [Member] | |||||
| Real Estate Properties [Line Items] | |||||
| Gain on sale | $ 35,100,000 | ||||
| 12 Vreeland Road [Member] | |||||
| Real Estate Properties [Line Items] | |||||
| Gain on sale from unconsolidated joint ventures | $ 0 | ||||
| Gain on sale | 2,000,000 | ||||
| Sale price | $ 2,000,000 | ||||
| Offices At Crystal Lake [Member] | |||||
| Real Estate Properties [Line Items] | |||||
| Gain on sale from unconsolidated joint ventures | $ (1,900,000) | $ (1,900,000) | |||
| Sale price | $ 1,900,000 | ||||
| Offices At Crystal Lake [Member] | Unconsolidated Joint Venture Office Buildings [Member] | |||||
| Real Estate Properties [Line Items] | |||||
| Gain on sale | (1,900,000) | ||||
| Sale price | $ 1,900,000 |