DEBT (Details)		9 Months Ended	12 Months Ended
		Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($) basisPoints
Secured and Unsecured Debt [Line Items]
Debt Instrument, Credit Rating		Baa2
Secured debt, net of debt issuance costs		$ 0	$ 2,031,000
Total debt		1,674,371,000	1,861,744,000
Unsecured Debt [Member]
Secured and Unsecured Debt [Line Items]
Long-Term Debt, total		1,680,000,000
Payments of principal over future years [Abstract]
2023 - Remainder of year		0
2024		170,000,000
2025		145,000,000
2026		140,000,000
2027		175,000,000
2028 and beyond		1,050,000,000
Long-Term Debt, total		$ 1,680,000,000
$100 million senior unsecured term loan (new in 2023)
Secured and Unsecured Debt [Line Items]
Debt Instrument, Term		7 years
Debt Instrument, Interest Rate, Effective Percentage		5.27%
Unsecured debt, carrying amount		$ 100,000,000
Debt instrument, basis spread above variable rate		0.0135
$65 million unsecured term loan (repaid in 2023)
Secured and Unsecured Debt [Line Items]
Debt Instrument, Interest Rate, Effective Percentage		2.31%
Long-term debt, carrying amount repaid		$ 65,000,000
$ 50 million senior unsecured notes (repaid in 2023)
Secured and Unsecured Debt [Line Items]
Debt Instrument, Interest Rate, Effective Percentage		3.80%
Long-term debt, carrying amount repaid		$ 50,000,000
Mortgage loan
Secured and Unsecured Debt [Line Items]
Debt Instrument, Maturity Date, Description		November 30, 2026
Long-term debt, carrying amount repaid		$ 1,905,000
Debt Instrument, Interest Rate, Stated Percentage		3.85%
$100 million senior unsecured term loan (refinanced in 2023)
Secured and Unsecured Debt [Line Items]
Debt Instrument, Interest Rate, Effective Percentage		2.61%
Unsecured debt, carrying amount		$ 100,000,000
Debt instrument, basis spread above variable rate		95
Debt instrument, reduction in basis spread		45
Line of Credit [Member}
Secured and Unsecured Debt [Line Items]
Long-term debt, gross		$ 0	170,000,000
Debt Issuance Costs, Gross		1,760,000	1,546,000
Long-Term Debt, total		(1,760,000)	168,454,000
Payments of principal over future years [Abstract]
Long-Term Debt, total		(1,760,000)	168,454,000
Unsecured Debt [Member]
Secured and Unsecured Debt [Line Items]
Long-term debt, gross	[1]	1,680,000,000	1,695,000,000
Debt Issuance Costs, Gross		3,869,000	3,741,000
Long-Term Debt, total		1,676,131,000	1,691,259,000
Payments of principal over future years [Abstract]
Long-Term Debt, total		1,676,131,000	1,691,259,000
Secured Debt [Member]
Secured and Unsecured Debt [Line Items]
Long-term debt, gross	[1]	0	2,041,000
Debt Issuance Costs, Gross		0	10,000
Long-Term Debt, total		0	2,031,000
Payments of principal over future years [Abstract]
Long-Term Debt, total		0	2,031,000
Bank credit facilities amended effective in 2023 - $625 and $50 million
Secured and Unsecured Debt [Line Items]
Line of Credit Facility, Borrowing Capacity		675,000,000
Bank credit facilities obtained in 2021 (former terms)
Secured and Unsecured Debt [Line Items]
Line of Credit Facility, Borrowing Capacity			$ 475,000,000
Line of credit, facility fee (in basis points) | basisPoints			15
Debt Instrument, Maturity Date, Description			July 30, 2025
Debt instrument, basis spread above variable rate			77.5
Nine bank group unsecured revolving credit facility [Member] | Bank credit facilities obtained in 2021 (former terms)
Secured and Unsecured Debt [Line Items]
Line of Credit Facility, Borrowing Capacity			$ 425,000,000
Pnc Na Unsecured revolving credit facility [Member] | Bank credit facilities obtained in 2021 (former terms)
Secured and Unsecured Debt [Line Items]
Line of Credit Facility, Borrowing Capacity			$ 50,000,000
Pnc Na Unsecured revolving credit facility [Member] | Bank credit facilities amended effective 2023 - $50 million
Secured and Unsecured Debt [Line Items]
Long-term debt, gross		$ 0
Line of Credit Facility, Interest Rate at Period End		6.185%
Line of Credit Facility, Borrowing Capacity		$ 50,000,000
Line of credit, facility fee (in basis points)		15
Debt Instrument, Maturity Date, Description		July 30, 2025
Extension option on credit facility		two six-month extensions
Debt instrument, basis spread above variable rate		77.5
Eleven bank group unsecured revolving credit facility | Bank credit facilities amended effective in 2023 - $625 and $50 million
Secured and Unsecured Debt [Line Items]
Initial pricing basis for credit facilities		BBB+/Baa1
Line of credit facility covenant terms, consolidated leverage ratio		32.50%
Eleven bank group unsecured revolving credit facility | Bank credit facilities amended effective 2023 - $625 million
Secured and Unsecured Debt [Line Items]
Long-term debt, gross		$ 0
Sustainability performance linked basis point reduction (in basis points)		1
Line of Credit Facility, Interest Rate at Period End		6.094%
Line of Credit Facility, Borrowing Capacity		$ 625,000,000
Line of credit, facility fee (in basis points)		15
Debt Instrument, Maturity Date, Description		July 30, 2025
Extension option on credit facility		two six-month extensions
Line of credit facility, accordion		$ 125,000,000
Line of Credit Facility, Increase (Decrease), Net		$ 200,000,000
Debt instrument, basis spread above variable rate		76.5
Standby Letters of Credit | Bank credit facilities amended effective 2023 - $625 million
Secured and Unsecured Debt [Line Items]
Letters of Credit Outstanding, Amount		$ 2,655,000

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