Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	190,000,000	190,000,000
Common stock, shares outstanding	90,596,723	90,595,176
Mack-Cali Realty LP [Member]
General partner common units outstanding	90,596,723	90,595,176
Limited partners common units outstanding	9,586,528	9,612,064