REAL ESTATE PROPERTIES 3 (Details)		12 Months Ended
		Dec. 31, 2018 USD ($) ft²	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
DEVELOPMENT [Abstract]
Interest costs capitalized on development properties		$ 6,334,000	$ 5,765,000	$ 5,340,000
Internal Development Costs Capitalized During Period		4,696,000	4,754,000	3,789,000
Improvements on developments transferred to real estate properties		8,556,000
Development costs incurred, for the period		167,667,000	$ 124,938,000	$ 203,765,000
Future Minimum payments receivable [Abstract]
2019		226,330,000
2020		195,850,000
2021		151,564,000
2022		112,007,000
2023		82,262,000
Thereafter		163,499,000
Total minimum receipts		$ 931,512,000
Lease Up [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		680,000
Development Costs Transferred	[1]	$ 9,815,000
Development costs incurred, for the period		39,689,000
Development and value-add properties		62,762,000
Estimated Total Cumulative Development Costs	[2]	$ 72,400,000
Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		1,584,000
Development Costs Transferred	[1]	$ 24,892,000
Development costs incurred, for the period		57,244,000
Development and value-add properties		87,098,000
Estimated Total Cumulative Development Costs	[2]	$ 133,800,000
Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		5,250,000
Development Costs Transferred	[1]	$ (35,729,000)
Development costs incurred, for the period		38,024,000
Development and value-add properties		$ 113,804,000
Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		1,719,000
Development Costs Transferred	[1]	$ 1,022,000
Development costs incurred, for the period		21,736,000
Development and value-add properties	[3]	$ 135,043,000
Lease Up Construction And Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		7,514,000
Development Costs Transferred	[1]	$ (1,022,000)
Development costs incurred, for the period		134,957,000
Development and value-add properties		263,664,000
Development obligations		52,400,000
Tenant improvement obligations		$ 13,600,000
Phoenix Area [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		315,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		6,809,000
Development and value-add properties		$ 6,809,000
Fort Myers [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		488,000
Development Costs Transferred	[1]	$ (2,704,000)
Development costs incurred, for the period		1,914,000
Development and value-add properties		$ 13,322,000
Miami [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		650,000
Development Costs Transferred	[1]	$ (9,110,000)
Development costs incurred, for the period		14,565,000
Development and value-add properties		$ 36,331,000
Orlando [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		214,000
Development Costs Transferred	[1]	$ (6,589,000)
Development costs incurred, for the period		1,188,000
Development and value-add properties		$ 5,719,000
Tampa [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		32,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		0
Development and value-add properties		$ 1,560,000
Atlanta [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		100,000
Development Costs Transferred	[1]	$ (705,000)
Development costs incurred, for the period		224,000
Development and value-add properties		$ 726,000
Jackson area [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		28,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		0
Development and value-add properties		$ 706,000
Charlotte [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		600,000
Development Costs Transferred	[1]	$ (1,366,000)
Development costs incurred, for the period		1,846,000
Development and value-add properties		$ 7,209,000
Austin [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		180,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		722,000
Development and value-add properties		$ 3,742,000
Dallas [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		612,000
Development Costs Transferred	[1]	$ (5,358,000)
Development costs incurred, for the period		7,954,000
Development and value-add properties		$ 12,192,000
Houston [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²	[4]	1,123,000
Development Costs Transferred	[1],[4]	$ (2,969,000)
Development costs incurred, for the period	[4]	(1,782,000)
Development and value-add properties	[4]	$ 16,439,000
San Antonio [Member] | Prospective Development [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		908,000
Development Costs Transferred	[1]	$ (6,928,000)
Development costs incurred, for the period		4,584,000
Development and value-add properties		$ 9,049,000
Siempre Viva Distribution Center [Member] | Lease Up [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		115,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		14,075,000
Development and value-add properties		14,075,000
Estimated Total Cumulative Development Costs	[2]	$ 14,400,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		01/19
Creekview 121 3 & 4 [Member] | Lease Up [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		158,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		3,489,000
Development and value-add properties		13,800,000
Estimated Total Cumulative Development Costs	[2]	$ 16,200,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		03/19
Falcon Field [Member] | Lease Up [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		96,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		5,285,000
Development and value-add properties		8,232,000
Estimated Total Cumulative Development Costs	[2]	$ 9,400,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		05/19
Gateway Commerce Park I [Member] | Lease Up [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		200,000
Development Costs Transferred	[1]	$ 9,110,000
Development costs incurred, for the period		11,131,000
Development and value-add properties		20,241,000
Estimated Total Cumulative Development Costs	[2]	$ 25,000,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		05/19
Broadmoor Commerce Park II [Member] | Lease Up [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		111,000
Development Costs Transferred	[1]	$ 705,000
Development costs incurred, for the period		5,709,000
Development and value-add properties		6,414,000
Estimated Total Cumulative Development Costs	[2]	$ 7,400,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		11/19
Horizon XI [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		135,000
Development Costs Transferred	[1]	$ 3,171,000
Development costs incurred, for the period		5,552,000
Development and value-add properties		8,723,000
Estimated Total Cumulative Development Costs	[2]	$ 10,400,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		01/20
Settlers Crossing 1 [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		77,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		4,704,000
Development and value-add properties		6,260,000
Estimated Total Cumulative Development Costs	[2]	$ 7,400,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		01/20
Settlers Crossing 2 [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		83,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		5,442,000
Development and value-add properties		7,115,000
Estimated Total Cumulative Development Costs	[2]	$ 8,400,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		01/20
SunCoast 5 [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		81,000
Development Costs Transferred	[1]	$ 2,704,000
Development costs incurred, for the period		3,831,000
Development and value-add properties		6,535,000
Estimated Total Cumulative Development Costs	[2]	$ 7,700,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		01/20
Airport Commerce Center 3 [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		96,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		4,060,000
Development and value-add properties		5,793,000
Estimated Total Cumulative Development Costs	[2]	$ 7,300,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		02/20
Parc North 5 [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		100,000
Development Costs Transferred	[1]	$ 1,683,000
Development costs incurred, for the period		5,270,000
Development and value-add properties		6,953,000
Estimated Total Cumulative Development Costs	[2]	$ 9,200,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		02/20
Steele Creek V [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		54,000
Development Costs Transferred	[1]	$ 1,366,000
Development costs incurred, for the period		1,948,000
Development and value-add properties		3,314,000
Estimated Total Cumulative Development Costs	[2]	$ 5,800,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		03/20
Horizon VI [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		148,000
Development Costs Transferred	[1]	$ 3,418,000
Development costs incurred, for the period		4,807,000
Development and value-add properties		8,225,000
Estimated Total Cumulative Development Costs	[2]	$ 12,700,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		04/20
Ten West Crossing 8 [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		132,000
Development Costs Transferred	[1]	$ 1,947,000
Development costs incurred, for the period		4,643,000
Development and value-add properties		6,590,000
Estimated Total Cumulative Development Costs	[2]	$ 10,900,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		04/20
Tri-County Crossing 1 & 2 [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		203,000
Development Costs Transferred	[1]	$ 2,012,000
Development costs incurred, for the period		6,883,000
Development and value-add properties		8,895,000
Estimated Total Cumulative Development Costs	[1]	$ 14,600,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		04/20
Eisenhauer Point 7 & 8 [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		336,000
Development Costs Transferred	[1]	$ 4,916,000
Development costs incurred, for the period		8,174,000
Development and value-add properties		13,090,000
Estimated Total Cumulative Development Costs	[2]	$ 24,500,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		05/20
Creekview 121 5 & 6 [Member] | Under construction [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		139,000
Development Costs Transferred	[1]	$ 3,675,000
Development costs incurred, for the period		1,930,000
Development and value-add properties		5,605,000
Estimated Total Cumulative Development Costs	[2]	$ 14,900,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		07/20
Alamo Ridge IV [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		97,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		320,000
Development and value-add properties	[3]	$ 7,417,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		03/18
Oak Creek VII [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		116,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		601,000
Development and value-add properties	[3]	$ 6,732,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		03/18
Weston [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		134,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		222,000
Development and value-add properties	[3]	$ 15,742,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		03/18
Progress Center 1 & 2 [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		132,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		143,000
Development and value-add properties	[3]	$ 10,476,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		04/18
Horizon X [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		104,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		3,352,000
Development and value-add properties	[3]	$ 6,902,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		05/18
SunCoast 4 [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		93,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		71,000
Development and value-add properties	[3]	$ 9,191,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		05/18
Country Club V [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		305,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		7,078,000
Development and value-add properties	[3]	$ 21,029,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		06/18
Eisenhauer Point 3 [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		71,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		231,000
Development and value-add properties	[3]	$ 6,390,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		06/18
Kyrene 202 III, IV & V [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		166,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		1,146,000
Development and value-add properties	[3]	$ 12,689,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		09/18
Steele Creek VII [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		120,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		795,000
Development and value-add properties	[3]	$ 8,592,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		09/18
Eisenhauer Point 6 [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		85,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		1,356,000
Development and value-add properties	[3]	$ 5,406,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		10/18
Horizon XII [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		140,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		653,000
Development and value-add properties	[3]	$ 11,883,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		10/18
Eisenhauer Point 5 [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		98,000
Development Costs Transferred	[1]	$ 0
Development costs incurred, for the period		2,012,000
Development and value-add properties	[3]	$ 7,816,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		11/18
West Road 5 [Member] | Development and value-add completed and transferred to Real estate properties [Member]
DEVELOPMENT [Abstract]
Size (Unaudited) (Square feet) | ft²		58,000
Development Costs Transferred	[1]	$ 1,022,000
Development costs incurred, for the period		3,756,000
Development and value-add properties	[3]	$ 4,778,000
Conversion date (or anticipated conversion date, if property is in lease-up or under construction)		11/18

[1] Represents costs transferred from Prospective Development (primarily land) to Under Construction during the period. Negative amounts represent land inventory costs transferred to Under Construction.

[2] Included in these costs are development obligations of $52.4 million and tenant improvement obligations of $13.6 million on properties under development.

[3] Represents cumulative costs at the date of transfer.

[4] Negative amount represents land inventory costs transferred to Under Construction and land sold on 3/28/18.