CONSOLIDATED STATEMENTS OF CASH FLOWS - Unaudited - USD ($)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
OPERATING ACTIVITIES
Net Income	$ 46,785,000	$ 49,483,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	56,462,000	51,037,000
Stock-based compensation expense	3,421,000	2,960,000
Net gain on sales of real estate investments and non-operating real estate	0	(11,406,000)
Gain on casualties and involuntary conversion on real estate assets	(161,000)	(100,000)
Changes in operating assets and liabilities:
Accrued income and other assets	570,000	2,167,000
Accounts payable, accrued expenses and prepaid rent	8,460,000	3,792,000
Other	1,145,000	454,000
NET CASH PROVIDED BY OPERATING ACTIVITIES	116,682,000	98,387,000
INVESTING ACTIVITIES
Development and value-add properties	(104,863,000)	(115,666,000)
Purchases of real estate	(6,231,000)	(62,068,000)
Real estate improvements	(18,167,000)	(16,963,000)
Net proceeds from sales of real estate investments and non-operating real estate	0	18,102,000
Proceeds from casualties and involuntary conversion on real estate assets	242,000	187,000
Repayments on mortgage loans receivable	14,000	19,000
Changes in accrued development costs	(181,000)	2,061,000
Changes in other assets and other liabilities	(17,475,000)	(10,514,000)
NET CASH USED IN INVESTING ACTIVITIES	(146,661,000)	(184,842,000)
FINANCING ACTIVITIES
Proceeds from unsecured bank credit facilities	318,115,000	377,133,000
Repayments on unsecured bank credit facilities	(363,787,000)	(376,983,000)
Proceeds from Unsecured Debt	100,000,000	80,000,000
Repayments on secured debt	(4,465,000)	(51,085,000)
Debt issuance costs	(584,000)	(168,000)
Distributions paid to stockholders (not including dividends accrued)	(59,157,000)	(53,161,000)
Proceeds from common stock offerings	44,381,000	113,436,000
Proceeds from dividend reinvestment plan	0	109,000
Other	(4,644,000)	(2,874,000)
NET CASH PROVIDED BY FINANCING ACTIVITIES	29,859,000	86,407,000
DECREASE IN CASH AND CASH EQUIVALENTS	(120,000)	(48,000)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	224,000	374,000
CASH AND CASH EQUIVALENTS AT END OF PERIOD	104,000	326,000
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for interest, net of amounts capitalized of $5,184 and $3,921 for 2020 and 2019, respectively	16,161,000	16,266,000
Cash paid for operating lease liabilities	719,000	636,000
NON-CASH OPERATING ACTIVITY
Operating lease liabilities arising from obtaining right of use assets	$ 495,000	$ 15,435,000