CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES:
Net income		$ 80,872,000	$ 80,872,000	$ 155,076,000	$ 87,340,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		39,216,000		37,555,000	37,610,000
Stock-based compensation expense		6,566,000		5,870,000	5,249,000
Impairment charges		5,500,000			1,880,000
Other than Temporary Impairment Losses, Investments	$ 5,500,000	5,500,000
Gain on sale of real estate, net		(2,106,000)		(70,682,000)	(3,814,000)
Income from unconsolidated joint ventures		(2,388,000)		(2,864,000)	(2,263,000)
Income distributions from unconsolidated joint ventures		2,991,000		2,371,000	1,738,000
Insurance proceeds for damaged property				2,619,000
Payment for remediation of damaged property				(508,000)
Straight-line rental income		(4,487,000)		(9,550,000)	(10,694,000)
Adjustment for collectability of rental income		1,926,000
Lease incentives funded		(387,000)		(1,272,000)	(6,544,000)
Amortization of lease incentives		385,000		2,092,000	2,209,000
Provision for (recovery of) doubtful accounts		166,000		87,000	(206,000)
Non-cash interest related to contingent liabilities				377,000	602,000
Non-cash income related to earn-out and related lease incentive write-off				(3,074,000)	(842,000)
Other non-cash items, net		1,016,000		1,180,000	1,282,000
Increase in interest receivable		(5,854,000)		(5,682,000)	(5,367,000)
Increase (decrease) in accrued interest payable		803,000		(1,096,000)	601,000
Net change in other assets and liabilities		(1,750,000)		3,036,000	(3,476,000)
Net cash provided by operating activities		122,469,000		115,535,000	105,305,000
INVESTING ACTIVITIES:
Investment in real estate properties		(58,414,000)		(40,408,000)	(82,405,000)
Investment in real estate developments		(20,524,000)		(35,279,000)	(22,901,000)
Investment in real estate capital improvements		(2,839,000)		(3,249,000)	(2,899,000)
Capitalized interest		(608,000)		(1,248,000)	(908,000)
Proceeds from sale of real estate, net		14,009,000		92,749,000	15,413,000
Investment in real estate mortgage loans receivable		(12,342,000)		(21,364,000)	(11,913,000)
Principal payments received on mortgage loans receivable		1,065,000		2,136,000	17,863,000
Investments in unconsolidated joint ventures		(472,000)		(670,000)	(3,848,000)
Proceeds from dissolution of unconsolidated joint ventures		6,601,000
Payment of working capital reserve					(439,000)
Advances and originations under notes receivable		(8,967,000)		(124,000)
Principal payments received on notes receivable		3,503,000		3,848,000	25,000
Net cash used in investing activities		(78,988,000)		(3,609,000)	(92,012,000)
FINANCING ACTIVITIES:
Bank borrowings		107,900,000		116,200,000	113,000,000
Repayment of bank borrowings		(126,000,000)		(100,700,000)	(123,600,000)
Proceeds from issuance of senior unsecured notes		100,000,000			100,000,000
Principal payments on senior unsecured notes		(33,667,000)		(38,166,000)	(31,167,000)
Proceeds from common stock issued				1,005,000	14,578,000
Stock option exercises		123,000		123,000	202,000
Distributions paid to stockholders		(90,899,000)		(90,372,000)	(90,219,000)
Contribution from non-controlling interests		965,000		3,963,000	3,488,000
Distributions paid to non-controlling interests		(309,000)		(65,000)
Financing costs paid		(61,000)		(3,162,000)	(363,000)
Other		(2,053,000)		(1,201,000)	(1,990,000)
Net cash used in financing activities		(44,001,000)		(112,375,000)	(16,071,000)
Decrease in cash, cash equivalents and restricted cash		(520,000)		(449,000)	(2,778,000)
Cash, cash equivalents and restricted cash, beginning of period		4,764,000		5,213,000	7,991,000
Cash, cash equivalents and restricted cash, end of period	$ 4,244,000	4,244,000	$ 4,244,000	4,764,000	5,213,000
Supplemental disclosure of cash flow information:
Interest paid		$ 28,767,000		$ 30,116,000	$ 28,070,000