UNSECURED AND SECURED DEBT (Details) - USD ($)		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Secured and Unsecured Debt [Line Items]
Unsecured debt, net of debt issuance costs		$ 1,242,570,000	$ 1,107,708,000
Secured debt, carrying amount		2,156,000	79,096,000
Carrying Amount of Securing Real Estate		8,515,000
Unsecured debt, carrying amount		1,245,000,000	1,110,000,000
Secured Debt		2,142,000	78,993,000
Unsecured bank credit facilities, net of debt issuance costs		207,066,000	124,194,000
Total debt		$ 1,451,778,000	$ 1,310,895,000
Weighted average interest rates (in hundredths)		1.01%	1.86%	3.34%
Repaid in 2021 - $40 million term loan (2016) [Member]
Secured and Unsecured Debt [Line Items]
Debt instrument, spread above LIBOR variable rate	[1]	1.10%
Effective interest rate	[1]	2.34%
Debt Instrument, Maturity Date	[1]	Jul. 30, 2021
Unsecured debt, carrying amount	[1]	$ 0	$ 40,000,000
$75 Million Unsecured Term Loan (2015) [Member]
Secured and Unsecured Debt [Line Items]
Debt instrument, spread above LIBOR variable rate	[1]	1.40%
Effective interest rate	[1]	3.03%
Debt Instrument, Maturity Date	[1]	Feb. 28, 2022
Unsecured debt, carrying amount	[1]	$ 75,000,000	75,000,000
$65 million term loan (2016) [Member]
Secured and Unsecured Debt [Line Items]
Debt instrument, spread above LIBOR variable rate	[1]	1.10%
Effective interest rate	[1]	2.31%
Debt Instrument, Maturity Date	[1]	Apr. 01, 2023
Unsecured debt, carrying amount	[1]	$ 65,000,000	65,000,000
Fifty million senior unsecured notes [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		3.80%
Debt Instrument, Maturity Date		Aug. 28, 2023
Unsecured debt, carrying amount		$ 50,000,000	50,000,000
Twenty million senior unsecured notes [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		3.80%
Debt Instrument, Maturity Date		Aug. 28, 2025
Unsecured debt, carrying amount		$ 20,000,000	20,000,000
Sixty million senior unsecured notes (executed in 2017) [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		3.46%
Debt Instrument, Maturity Date		Dec. 13, 2024
Unsecured debt, carrying amount		$ 60,000,000	60,000,000
Sixty million senior unsecured notes (executed in 2016) [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		3.48%
Debt Instrument, Maturity Date		Dec. 15, 2024
Unsecured debt, carrying amount		$ 60,000,000	60,000,000
Forty million senior unsecured notes (executed in 2016) [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		3.75%
Debt Instrument, Maturity Date		Dec. 15, 2026
Unsecured debt, carrying amount		$ 40,000,000	40,000,000
Twenty-five million senior unsecured notes (executed in 2015) [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		3.97%
Debt Instrument, Maturity Date		Oct. 01, 2025
Unsecured debt, carrying amount		$ 25,000,000	25,000,000
Fifty million senior unsecured notes (executed in 2015) [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		3.99%
Debt Instrument, Maturity Date		Oct. 07, 2025
Unsecured debt, carrying amount		$ 50,000,000	50,000,000
Sixty million senior unsecured notes (executed in 2018) [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		3.93%
Debt Instrument, Maturity Date		Apr. 10, 2028
Unsecured debt, carrying amount		$ 60,000,000	60,000,000
$80 million senior unsecured private placement notes (2019) [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		4.27%
Debt Instrument, Maturity Date		Mar. 28, 2029
Unsecured debt, carrying amount		$ 80,000,000	80,000,000
$35 million senior unsecured private placement notes (2019) [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		3.54%
Debt Instrument, Maturity Date		Aug. 15, 2031
Unsecured debt, carrying amount		$ 35,000,000	35,000,000
$75 million senior unsecured private placement notes (2019) [Member]
Secured and Unsecured Debt [Line Items]
Effective interest rate		3.47%
Debt Instrument, Maturity Date		Aug. 19, 2029
Unsecured debt, carrying amount		$ 75,000,000	75,000,000
$100 million term loan (2019) [Member]
Secured and Unsecured Debt [Line Items]
Debt instrument, spread above LIBOR variable rate	[1],[2]	0.85%
Effective interest rate	[1],[2]	2.10%
Debt Instrument, Maturity Date	[1],[2]	Oct. 10, 2026
Unsecured debt, carrying amount	[1],[2]	$ 100,000,000	100,000,000
Spread above LIBOR, before refinance		1.50%
Effective interest rate, before refinance		2.75%
Secured and unsecured debt [Member]
Secured and Unsecured Debt [Line Items]
Long-term Debt, Maturities, Repayments of Principal in 2022		$ 75,115,000
Long-term Debt, Maturities, Repayments of Principal in 2023		115,119,000
Long-term Debt, Maturities, Repayments of Principal in 2024		120,122,000
Long-term Debt, Maturities, Repayments of Principal in 2025		145,128,000
Long-term Debt, Maturities, Repayments of Principal in 2026		$ 141,672,000
$100 million term loan (2020)
Secured and Unsecured Debt [Line Items]
Debt instrument, spread above LIBOR variable rate	[1]	1.45%
Effective interest rate	[1]	2.39%
Debt Instrument, Maturity Date	[1]	Mar. 25, 2027
Unsecured debt, carrying amount	[1]	$ 100,000,000	100,000,000
$100 million senior unsecured private placement notes (2020)
Secured and Unsecured Debt [Line Items]
Effective interest rate		2.61%
Debt Instrument, Maturity Date		Oct. 14, 2030
Unsecured debt, carrying amount		$ 100,000,000	100,000,000
$75 million senior unsecured private placement notes (2020)
Secured and Unsecured Debt [Line Items]
Effective interest rate		2.71%
Debt Instrument, Maturity Date		Oct. 14, 2032
Unsecured debt, carrying amount		$ 75,000,000	75,000,000
$50 million unsecured term loan (2021)
Secured and Unsecured Debt [Line Items]
Debt instrument, spread above LIBOR variable rate	[1]	1.00%
Effective interest rate	[1]	1.55%
Debt Instrument, Maturity Date	[1]	Mar. 18, 2025
Unsecured debt, carrying amount	[1]	$ 50,000,000	0
Debt Instrument, Term		4 years
$125 million senior unsecured private placement notes (2021)
Secured and Unsecured Debt [Line Items]
Effective interest rate		2.74%
Debt Instrument, Maturity Date		Jun. 10, 2031
Unsecured debt, carrying amount		$ 125,000,000	0
Debt Instrument, Term		10 years
$100 million term loan (2021 refinance)
Secured and Unsecured Debt [Line Items]
Effective interest rate		2.10%
Unsecured debt, carrying amount		$ 100,000,000
Debt Instrument, Term		5 years
Sustainability-linked pricing component, interest margin reduction (in basis points)		1
Spread over LIBOR, current interest rate (in basis points)		85
Spread over LIBOR, reduction in interest rate (in basis points)		65
Mortgage loan repaid in March 2021 - Colorado Crossing, Interstate I-III, Rojas, Steele Creek 1 & 2, Venture and World Houston 3-9
Secured and Unsecured Debt [Line Items]
Secured debt, carrying amount		$ 0	41,610,000
Interest Rate (in hundredths)		4.75%
Monthly P & I Payment		$ 420,045
Maturity Date		Repaid
Carrying Amount of Securing Real Estate		$ 0
Debt Instrument, Maturity Date		Jun. 05, 2021
Mortgage loan balance repaid		$ 40,800,000
Interest rate of mortgage loan repaid		4.75%
Mortgage loan repaid in October 2021 - Arion 18, Beltway VI & VII, Commerce Park II & III, Concord Distribution Center, Interstate Distribution Center V, VI & VII, Lakeview Business Center, Ridge Creek Distribution Center II, Southridge IV & V and World Houston 32 [Member]
Secured and Unsecured Debt [Line Items]
Secured debt, carrying amount		$ 0	35,220,000
Interest Rate (in hundredths)		4.09%
Monthly P & I Payment		$ 329,796
Maturity Date		Repaid
Carrying Amount of Securing Real Estate		$ 0
Debt Instrument, Maturity Date		Jan. 05, 2022
Mortgage loan balance repaid		$ 33,100,000
Interest rate of mortgage loan repaid		4.09%
Ramona Distribution Center [Member]
Secured and Unsecured Debt [Line Items]
Secured debt, carrying amount		$ 2,156,000	2,266,000
Interest Rate (in hundredths)		3.85%
Monthly P & I Payment		$ 16,287
Maturity Date		11/30/2026
Carrying Amount of Securing Real Estate		$ 8,515,000
Notes Payable to Banks [Member]
Secured and Unsecured Debt [Line Items]
Unsecured bank credit facilities - variable rate, carrying amount		209,210,000	125,000,000
Unamortized debt issuance costs		2,144,000	806,000
Unsecured bank credit facilities, net of debt issuance costs		207,066,000	124,194,000
Unsecured Debt [Member]
Secured and Unsecured Debt [Line Items]
Unsecured debt, net of debt issuance costs		1,242,570,000	1,107,708,000
Unsecured debt, carrying amount	[3]	1,245,000,000	1,110,000,000
Unamortized debt issuance costs		2,430,000	2,292,000
Secured Debt [Member]
Secured and Unsecured Debt [Line Items]
Secured debt, carrying amount	[3]	2,156,000	79,096,000
Unamortized debt issuance costs		14,000	103,000
Secured Debt		$ 2,142,000	$ 78,993,000

[1] The interest rates on these unsecured term loans are comprised of LIBOR plus a margin which is subject to a pricing grid for changes in the Company’s coverage ratings. The Company entered into interest rate swap agreements (further described in Note 12) to convert the loans’ LIBOR rates to effectively fixed interest rates. The interest rates in the table above are the effectively fixed interest rates for the loans, including the effects of the interest rate swaps, as of December 31, 2021.

[2] This term loan was refinanced during 2021. Effective October 10, 2021, the margin above LIBOR was reduced from 1.50% to 0.85% reducing the effectively fixed rate from 2.75% to 2.10%

[3] These loans have a fixed interest rate or an effectively fixed interest rate due to interest rate swaps.