CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES:
Net income	$ 155,076,000	$ 87,340,000	$ 85,115,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	37,555,000	37,610,000	35,932,000
Stock-based compensation expense	5,870,000	5,249,000	4,280,000
Impairment charges		1,880,000	766,000
Gain on sale of real estate, net	(70,682,000)	(3,814,000)	(3,582,000)
Income from unconsolidated joint ventures	(2,864,000)	(2,263,000)	(1,138,000)
Income distributions from unconsolidated joint ventures	2,371,000	1,738,000	1,695,000
Insurance proceeds for damaged property	2,619,000
Payment for remediation of damaged property	(508,000)
Straight-line rental income	(9,550,000)	(10,694,000)	(13,477,000)
Lease incentives funded	(1,272,000)	(6,544,000)	(4,827,000)
Amortization of lease incentives	2,092,000	2,209,000	1,955,000
Provision for doubtful accounts	87,000	(206,000)	457,000
Non-cash interest related to contingent liabilities	377,000	602,000	684,000
Non-cash income related to earn-out and related lease incentive write-off	(3,074,000)	(842,000)	(16,000)
Other non-cash items, net	1,180,000	1,282,000	1,216,000
Increase in interest receivable	(5,682,000)	(5,367,000)	(5,147,000)
(Decrease) increase in accrued interest payable	(1,096,000)	601,000	701,000
Net change in other assets and liabilities	3,036,000	(3,476,000)	1,094,000
Net cash provided by operating activities	115,535,000	105,305,000	105,708,000
INVESTING ACTIVITIES:
Investment in real estate properties	(40,408,000)	(82,405,000)	(74,923,000)
Investment in real estate developments	(35,279,000)	(22,901,000)	(42,342,000)
Investment in real estate capital improvements	(3,249,000)	(2,899,000)	(6,792,000)
Capitalized interest	(1,248,000)	(908,000)	(1,408,000)
Proceeds from sale of real estate, net	92,749,000	15,413,000	17,369,000
Investment in real estate mortgage loans receivable	(21,364,000)	(11,913,000)	(20,685,000)
Principal payments received on mortgage loans receivable	2,136,000	17,863,000	8,278,000
Investments in unconsolidated joint ventures	(670,000)	(3,848,000)	(1,770,000)
Payment of working capital reserve		(439,000)	(2,756,000)
Advances and originations under notes receivable	(124,000)		(14,969,000)
Principal payments received on notes receivable	3,848,000	25,000	100,000
Net cash used in investing activities	(3,609,000)	(92,012,000)	(139,898,000)
FINANCING ACTIVITIES:
Bank borrowings	116,200,000	113,000,000	123,600,000
Repayment of bank borrowings	(100,700,000)	(123,600,000)	(137,000,000)
Proceeds from issuance of senior unsecured notes		100,000,000	77,500,000
Principal payments on senior unsecured notes	(38,166,000)	(31,167,000)	(26,667,000)
Proceeds from common stock issued	1,005,000	14,578,000	78,592,000
Stock option exercises	123,000	202,000	159,000
Distributions paid to stockholders	(90,372,000)	(90,219,000)	(84,568,000)
Contribution from non-controlling interests	3,963,000	3,488,000
Distributions paid to non-controlling interests	(65,000)
Financing costs paid	(3,162,000)	(363,000)	(147,000)
Other	(1,201,000)	(1,990,000)	(2,230,000)
Net cash (used in) provided by financing activities	(112,375,000)	(16,071,000)	29,239,000
Decrease in cash, cash equivalents and restricted cash	(449,000)	(2,778,000)	(4,951,000)
Cash, cash equivalents and restricted cash, beginning of period	5,213,000	7,991,000	12,942,000
Cash, cash equivalents and restricted cash, end of period	4,764,000	5,213,000	7,991,000
Supplemental disclosure of cash flow information:
Interest paid	$ 30,116,000	$ 28,070,000	$ 24,490,000