REAL ESTATE PROPERTIES - Sales of Real Estate (Details)		12 Months Ended
		Dec. 31, 2020 USD ($) ft²	Dec. 31, 2019 USD ($) ft² a	Dec. 31, 2018 USD ($) ft²
Real Estate Properties [Line Items]
Net Sales Price of Real Estate Sold		$ 20,510,000	$ 66,559,000	$ 22,004,000
Basis		7,365,000	25,491,000	7,731,000
Gain on Sales of Real Estate Investments		$ 13,145,000	$ 41,068,000	14,273,000
Land [Member]
Real Estate Properties [Line Items]
SIze (in acres) of land sold | a			0.2
Proceeds from Sale of Property, Plant, and Equipment			$ 185,000	2,577,000
Gain on sales of land			$ 83,000	$ 86,000
University Business Center 120 [Member]
Real Estate Properties [Line Items]
Less Than Wholly Owned Joint Venture Investment Ownership Percentage		80.00%
Less Than Wholly Owned Joint Venture Investment Ownership Percentage Sold		80.00%
Less Than Wholly Owned Joint Venture Investment Ownership Percentage Sold, shown in table		80.00%
Less Than Wholly Owned Joint Venture Investment Ownership Percentage			80.00%
University Business Center 130 [Member]
Real Estate Properties [Line Items]
Less Than Wholly Owned Joint Venture Investment Ownership Percentage			80.00%
Less Than Wholly Owned Joint Venture Investment Ownership Percentage			20.00%
University Business Center 120 [Member]
Real Estate Properties [Line Items]
Size (in square feet) of property sold | ft²	[1]	46,000
Date Of Property Sale	[1]	12/01/2020
Net Sales Price of Real Estate Sold	[1]	$ 10,342,000
Basis	[1]	4,007,000
Gain on Sales of Real Estate Investments	[1]	$ 6,335,000
Central Green Distribution Center [Member]
Real Estate Properties [Line Items]
Size (in square feet) of property sold | ft²		80,000
Date Of Property Sale		12/23/2020
Net Sales Price of Real Estate Sold		$ 10,168,000
Basis		3,358,000
Gain on Sales of Real Estate Investments		$ 6,810,000
World Houston International Business Ctr 5 [Member]
Real Estate Properties [Line Items]
Size (in square feet) of property sold | ft²			51,000
Date Of Property Sale			01/29/2019
Net Sales Price of Real Estate Sold			$ 3,679,000
Basis			1,354,000
Gain on Sales of Real Estate Investments			$ 2,325,000
Altamonte Commerce Center [Member]
Real Estate Properties [Line Items]
Size (in square feet) of property sold | ft²			186,000
Date Of Property Sale			05/20/2019
Net Sales Price of Real Estate Sold			$ 14,423,000
Basis			5,342,000
Gain on Sales of Real Estate Investments			$ 9,081,000
University Business Center 130 [Member]
Real Estate Properties [Line Items]
Size (in square feet) of property sold | ft²	[2]		40,000
Date Of Property Sale	[2]		11/07/2019
Net Sales Price of Real Estate Sold	[2]		$ 11,083,000
Basis	[2]		2,729,000
Gain on Sales of Real Estate Investments	[2]		$ 8,354,000
Southpointe Distribution Center [Member]
Real Estate Properties [Line Items]
Size (in square feet) of property sold | ft²			207,000
Date Of Property Sale			12/03/2019
Net Sales Price of Real Estate Sold			$ 13,699,000
Basis			2,281,000
Gain on Sales of Real Estate Investments			$ 11,418,000
University Business Center 125 and 175 [Member]
Real Estate Properties [Line Items]
Size (in square feet) of property sold | ft²			133,000
Date Of Property Sale			12/11/2019
Net Sales Price of Real Estate Sold			$ 23,675,000
Basis			13,785,000
Gain on Sales of Real Estate Investments			$ 9,890,000
World Houston International Business Ctr 18 [Member]
Real Estate Properties [Line Items]
Size (in square feet) of property sold | ft²				33,000
Date Of Property Sale				01/26/2018
Net Sales Price of Real Estate Sold				$ 2,289,000
Basis				1,211,000
Gain on Sales of Real Estate Investments				$ 1,078,000
56th Street Commerce Park [Member]
Real Estate Properties [Line Items]
Size (in square feet) of property sold | ft²				181,000
Date Of Property Sale				03/20/2018
Net Sales Price of Real Estate Sold				$ 12,032,000
Basis				2,888,000
Gain on Sales of Real Estate Investments				$ 9,144,000
35th Avenue Distribution Center [Member]
Real Estate Properties [Line Items]
Size (in square feet) of property sold | ft²				125,000
Date Of Property Sale				07/26/2018
Net Sales Price of Real Estate Sold				$ 7,683,000
Basis				3,632,000
Gain on Sales of Real Estate Investments				$ 4,051,000

[1] EastGroup owned 80% of University Business Center 120 through a joint venture partnership. EastGroup sold its 80% share of the joint venture, and the partnership was dissolved. The information shown for this transaction represents EastGroup's 80% ownership.

[2] EastGroup owned 80% of University Business Center 130 through a joint venture partnership. The information shown for this transaction also includes the 20% attributable to the Company's noncontrolling interest partner.