Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net earnings	$ 62,731,000	$ 44,828,000
Adjustments to reconcile net earnings to net cash flow provided by operating activities:
Depreciation and amortization expense	29,514,000	25,980,000
Impairment charges	2,227,000	2,730,000
Gain on dispositions of real estate	(7,646,000)	(9,550,000)
Deferred rent receivable	(2,445,000)	(2,158,000)
Amortization of above-market and below-market leases	13,000	(69,000)
Amortization of investment in direct financing leases	3,964,000	3,576,000
Amortization of debt issuance costs	706,000	778,000
Accretion expense	1,037,000	1,270,000
Stock-based compensation	3,543,000	2,974,000
Changes in assets and liabilities:
Accounts receivable	(876,000)	(700,000)
Prepaid expenses and other assets	(1,148,000)	(700,000)
Environmental remediation obligations	(21,086,000)	(4,549,000)
Accounts payable and accrued liabilities	(2,663,000)	(5,722,000)
Net cash flow provided by operating activities	67,871,000	58,688,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Property acquisitions	(63,288,000)	(126,645,000)
Capital expenditures		(271,000)
Addition to construction in progress	(49,000)	(188,000)
Proceeds from dispositions of real estate	11,610,000	11,059,000
Deposits for property acquisitions		3,298,000
Issuance of notes and mortgages receivable	(10,357,000)	(12,275,000)
Collection of notes and mortgages receivable	1,165,000	5,359,000
Net cash flow used in investing activities	(60,919,000)	(119,663,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under credit agreement	20,000,000	70,000,000
Repayments under credit agreement	(80,000,000)	(52,500,000)
Proceeds from senior unsecured notes	100,000,000
Payment of debt issuance costs	(587,000)
Payment of finance lease obligations	(355,000)	(507,000)
Security deposits refunded	(50,000)	440,000
Payments of cash dividends	(58,660,000)	(52,748,000)
Payments in settlement of restricted stock units	(496,000)	(728,000)
Net cash flow provided by (used in) financing activities	(20,295,000)	12,965,000
Change in cash, cash equivalents and restricted cash	(13,343,000)	(48,010,000)
Cash, cash equivalents and restricted cash at beginning of period	26,461,000	57,054,000
Cash, cash equivalents and restricted cash at end of period	13,118,000	9,044,000
Supplemental disclosures of cash flow information Cash paid during the period for:
Interest	19,536,000	17,729,000
Income taxes	653,000	399,000
Environmental remediation obligations	3,159,000	3,299,000
Non-cash transactions:
Dividends declared but not yet paid	19,619,000	18,043,000
Issuance of notes and mortgages receivable related to property dispositions	1,050,000
ATM Program [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock, net	$ (147,000)	$ 49,008,000