Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	190,000,000	190,000,000
Common stock, shares outstanding	90,947,387	90,712,417
Mack-Cali Realty LP [Member]
General Partner common units outstanding	90,947,387	90,712,417
Limited partners common units outstanding	9,021,400	9,649,031