| Mack-Cali Realty Corporation Stockholders' Equity (Stock Options Plans) (Narrative) (Details) (USD $) | 3 Months Ended | 9 Months Ended | 12 Months Ended | 9 Months Ended | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | Dec. 31, 2012 | May 31, 2013
 2013 Incentive Stock Plan [Member] | May 31, 2004
 2004 Incentive Stock Plan [Member] | Sep. 30, 2013
 2013 And 2004 Incentive Stock Plans [Member] | Sep. 30, 2013
 Employee And Director Plan [Member]
 Minimum [Member] | Sep. 30, 2013
 Employee And Director Plan [Member]
 Maximum [Member] | Sep. 30, 2013
 2000 Employee Plan [Member]
 Minimum [Member] | Sep. 30, 2013
 2000 Employee Plan [Member]
 Maximum [Member] | Sep. 30, 2013
 2000 Director Plan [Member]
 Minimum [Member] | Sep. 30, 2013
 2000 Director Plan [Member]
 Maximum [Member] | Sep. 30, 2013
 Employee Plan [Member] | Sep. 30, 2013
 2000 Director Plan And Director Plan [Member] | |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||||||||||
| Reserved stocks for issuance | 4,600,000 | 2,500,000 | 2,700,000 | 4,350,000 | 2,500,000 | 4,000,000 | 200,000 | 350,000 | ||||||||
| Shares issued | 0 | |||||||||||||||
| Exercisable time period | 5 years | 1 year | ||||||||||||||
| Stock option terms | 10 years | |||||||||||||||
| Weighted average remaining contractual life | 1 year | 1 month 6 days | ||||||||||||||
| Proceeds from stock options exercised | $ 0 | $ 0 | $ 0 | $ 0 | ||||||||||||
| Total intrinsic value of options exercised | 0 | 0 | 0 | 0 | ||||||||||||
| Stock options expense | $ 0 | $ 0 | $ 0 | $ 0 | ||||||||||||
| X | ||||||||||
| 
- Definition Stock option terms, years. No definition available. 
 | 
| X | ||||||||||
| 
- Definition Aggregate number of common shares reserved for future issuance. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
 | 
| X | ||||||||||
| 
- Definition Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
 | 
| X | ||||||||||
| 
- Definition The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
 | 
| X | ||||||||||
| 
- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
 | 
| X | ||||||||||
| 
- Details 
 | 
| X | ||||||||||
| 
- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
 | 
| X | ||||||||||
| 
- Definition Weighted average remaining contractual term of exercisable stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
 | 
| X | ||||||||||
| 
- Definition The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
 |