Noncontrolling Interests In Subsidiaries (Narrative) (Details) $ in Millions |
6 Months Ended | 12 Months Ended | |
|---|---|---|---|
|
Jun. 30, 2017
USD ($)
shares
|
Dec. 31, 2017
property
shares
|
Dec. 31, 2016
USD ($)
|
|
| Noncontrolling Interest [Line Items] | |||
| Number of common shares received upon redemption of common units | shares | 1 | ||
| Rebalance of ownership percentage | $ 4.6 | ||
| Percentage of noncontrolling interest | 10.40% | 10.50% | |
| Cash consideration | $ 2.0 | ||
| Issuance of common units | shares | 99,412 | ||
| Common unit value | $ 2.8 | ||
| Participation Rights [Member] | |||
| Noncontrolling Interest [Line Items] | |||
| Number of properties | property | 2 | ||
| Excess net cash flow remaining after the distribution to the Company | 50.00% | ||
| Internal rate of return | 10.00% | ||
| Mack-Cali Realty LP [Member] | |||
| Noncontrolling Interest [Line Items] | |||
| Cash consideration | $ 2.0 | ||
| Issuance of common units | shares | 99,412 | ||
| Common unit value | $ 2.8 | ||
| Future Developments [Member] | Participation Rights [Member] | |||
| Noncontrolling Interest [Line Items] | |||
| Number of properties | property | 1 | ||