CONSOLIDATED STATEMENTS OF CASH FLOWS - Unaudited - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
OPERATING ACTIVITIES
Net Income	$ 49,483,000	$ 47,012,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	51,037,000	44,493,000
Stock-based compensation expense	2,960,000	2,823,000
Net gain on sales of real estate investments and non-operating real estate	(11,406,000)	(10,308,000)
Gain on casualties and involuntary conversion on real estate assets	(100,000)	(1,150,000)
Changes in operating assets and liabilities:
Accrued income and other assets	2,167,000	2,111,000
Accounts payable, accrued expenses and prepaid rent	3,792,000	(12,075,000)
Other	454,000	828,000
NET CASH PROVIDED BY OPERATING ACTIVITIES	98,387,000	73,734,000
INVESTING ACTIVITIES
Development and value-add properties	(115,666,000)	(61,023,000)
Purchases of real estate	(62,068,000)	(27,660,000)
Real estate improvements	(16,963,000)	(16,126,000)
Net proceeds from sales of real estate investments and non-operating real estate	18,102,000	16,826,000
Proceeds from casualties and involuntary conversion on real estate assets	187,000	890,000
Repayments on mortgage loans receivable	19,000	1,958,000
Changes in accrued development costs	2,061,000	7,350,000
Changes in other assets and other liabilities	(10,514,000)	(5,240,000)
NET CASH USED IN INVESTING ACTIVITIES	(184,842,000)	(83,025,000)
FINANCING ACTIVITIES
Proceeds from unsecured bank credit facilities	377,133,000	216,672,000
Repayments on unsecured bank credit facilities	(376,983,000)	(233,989,000)
Proceeds from Unsecured Debt	80,000,000	60,000,000
Repayments on Unsecured Debt	0	(50,000,000)
Repayments on secured debt	(51,085,000)	(5,570,000)
Debt issuance costs	(168,000)	(1,845,000)
Distributions paid to stockholders (not including dividends accrued)	(53,161,000)	(45,449,000)
Proceeds from common stock offerings	113,436,000	74,789,000
Proceeds from dividend reinvestment plan	109,000	112,000
Other	(2,874,000)	(5,193,000)
NET CASH PROVIDED BY FINANCING ACTIVITIES	86,407,000	9,527,000
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(48,000)	236,000
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	374,000	16,000
CASH AND CASH EQUIVALENTS AT END OF PERIOD	326,000	252,000
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for interest, net of amount capitalized of $3,921 and $3,003 for 2019 and 2018, respectively	16,266,000	16,528,000
Cash paid for operating lease liabilities	636,000	0
NON-CASH OPERATING ACTIVITY
Operating lease liabilities arising from obtaining right of use assets	$ 15,435,000	$ 0