Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Earnings Per Share Tables - Basic Computation Of EPS) (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Stockolders Equity [Line Items]

Net income (loss)

$ 252,554

$ 80,267

$ 10,840

Add (deduct): Noncontrolling interests in consolidated joint ventures

3,904

1,216

1,018

Add (deduct): Noncontrolling interests in Operating Partnership

(23,685)

(6,866)

(341)

Add (deduct): Redeemable noncontrolling interests

(22,615)

(13,979)

(8,840)

Add (deduct): Redeemable noncontrolling interest

(22,615)

(13,979)

(8,840)

Add (deduct): Redemption value adjustment of redeemable noncontrolling interests attributable to common shareholders

(25,885)

(11,425)

(17,951)

Income (loss) from continuing operations available to common shareholders

184,273

49,213

(15,274)

Income from discontinued operations available to common shareholders

(98,297)

23,473

20,508

Net income (loss) available to common shareholders for basic earnings per share

$ 85,976

$ 72,686

$ 5,234

Weighted average common shares

90,557

90,388

90,005

Income (loss) from continuing operations available to common shareholders

$ 0.53

$ (0.64)

$ (0.45)

$ 2.59

$ 0.37

$ (0.12)

$ (0.13)

$ 0.42

$ 2.03

$ 0.54

$ (0.17)

Income from discontinued operations available to common shareholders

(1.17)

(0.01)

0.02

0.08

0.07

0.08

0.03

(1.08)

0.26

0.23

Net income available to common unitholders

(0.64)

(0.65)

(0.43)

2.67

0.45

(0.05)

0.45

$ 0.95

$ 0.80

$ 0.06

Mack-Cali Realty LP [Member]

Stockolders Equity [Line Items]

Net income (loss)

$ 252,554

$ 80,267

$ 10,840

Add (deduct): Noncontrolling interests in consolidated joint ventures

3,904

1,216

1,018

Add (deduct): Redeemable noncontrolling interests

(22,615)

(13,979)

(8,840)

Add (deduct): Redemption value adjustment of redeemable noncontrolling interests attributable to common shareholders

(28,740)

(12,721)

(20,025)

Income (loss) from continuing operations available to common shareholders

205,103

54,783

(17,007)

Income from discontinued operations available to common shareholders

(108,718)

26,134

22,878

Net income (loss) available to common shareholders for basic earnings per share

$ 96,385

$ 80,917

$ 5,871

Weighted average common units

100,520

100,634

100,410

Income (loss) from continuing operations available to common shareholders

0.53

(0.64)

(0.45)

2.59

0.37

(0.12)

(0.13)

0.42

$ 2.03

$ 0.54

$ (0.17)

Income from discontinued operations available to common shareholders

(1.17)

(0.01)

0.02

0.08

0.07

0.08

0.03

(1.08)

0.26

0.23

Net income available to common unitholders

$ (0.64)

$ (0.65)

$ (0.43)

$ 2.67

$ 0.45

$ (0.05)

$ 0.45

$ 0.95

$ 0.80

$ 0.06