CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
OPERATING ACTIVITIES:
Net income	$ 68,936,000	$ 25,377,000	$ 89,295,000	$ 46,890,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			18,712,000	18,667,000
Stock-based compensation expense			2,897,000	2,684,000
Impairment charges		1,880,000		1,880,000
Gain on sale of real estate, net	(48,345,000)	(5,054,000)	(48,345,000)	(5,054,000)
Income from unconsolidated joint ventures	(726,000)	(575,000)	(1,357,000)	(1,020,000)
Income distributions from unconsolidated joint ventures			1,256,000	754,000
Insurance proceeds for damaged property	2,619,000		2,619,000
Payment for remediation of damaged property			(173,000)
Straight-line rental income			(5,440,000)	(5,307,000)
Lease incentives funding			(1,017,000)	(5,172,000)
Amortization of lease incentives			1,091,000	1,111,000
Provision for doubtful accounts	(38,000)	(5,000)	(30,000)	(43,000)
Non-cash interest related to contingent liabilities			251,000	351,000
Other non-cash items, net			663,000	637,000
Increase in interest receivable			(2,814,000)	(2,572,000)
Decrease in accrued interest payable			(171,000)	(132,000)
Net change in other assets and liabilities			(1,966,000)	(6,336,000)
Net cash provided by operating activities			55,471,000	47,338,000
INVESTING ACTIVITIES:
Investment in real estate properties			(25,902,000)	(54,740,000)
Investment in real estate developments			(18,623,000)	(9,155,000)
Investment in real estate capital improvements			(1,763,000)	(2,195,000)
Capitalized interest			(552,000)	(371,000)
Proceeds from sale of real estate, net			64,386,000	14,106,000
Investment in real estate mortgage loans receivable			(11,654,000)	(7,829,000)
Principal payments received on mortgage loans receivable			1,636,000	17,339,000
Investments in unconsolidated joint ventures			(497,000)	(3,734,000)
Payment of working capital reserve				(439,000)
Principal payments received on notes receivable			2,352,000	25,000
Net cash provided by (used in) investing activities			9,383,000	(46,993,000)
FINANCING ACTIVITIES:
Bank borrowings			54,000,000	48,500,000
Repayment of bank borrowings			(65,000,000)	(110,600,000)
Proceeds from issuance of senior unsecured notes				100,000,000
Principal payments on senior unsecured notes			(4,166,000)	(4,167,000)
Proceeds from common stock issued				14,578,000
Stock option exercises			123,000	79,000
Distributions paid to stockholders			(45,168,000)	(45,110,000)
Contribution from non-controlling interests			1,081,000
Financing costs paid			(3,051,000)	(363,000)
Other			(1,180,000)	(1,954,000)
Net cash (used in) provided by financing activities			(63,361,000)	963,000
Increase in cash, cash equivalents and restricted cash			1,493,000	1,308,000
Cash, cash equivalents and restricted cash, beginning of period			5,213,000	7,991,000	$ 7,991,000
Cash, cash equivalents and restricted cash, end of period	$ 6,706,000	$ 9,299,000	6,706,000	9,299,000	$ 5,213,000
Supplemental disclosure of cash flow information:
Interest paid			$ 14,994,000	$ 14,119,000