Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ (15,944)	$ 8,378	$ 35,014
Adjustments to reconcile net income or loss to net cash provided by operating activities:
Depreciation and amortization expense	103,743	95,243	93,426
Amortization of above and below market leases	(1,031)	(496)	(158)
Hedge ineffectiveness	1,878	(1,878)
(Gain) loss on sale of properties and properties held for sale, less applicable income tax	18,481	2,938	(23,662)
Equity in losses of non-consolidated REITs	3,604	831	1,451
Increase in allowance for doubtful accounts	150	(30)	(195)
Changes in operating assets and liabilities:
Restricted cash	(15)	(8)	719
Tenant rent receivables	(160)	(185)	2,030
Straight-line rents	(1,767)	(1,977)	(2,448)
Lease acquisition costs	(2,052)	(1,095)	(1,487)
Prepaid expenses and other assets	(403)	(721)	422
Accounts payable, accrued expenses and other items	3,870	5,751	5,505
Accrued compensation	(143)	58	(32)
Tenant security deposits	28	526	581
Payment of deferred leasing commissions	(14,309)	(12,965)	(8,276)
Net cash provided by operating activities	95,930	94,370	102,890
Cash flows from investing activities:
Property acquisitions		(221,119)	(66,104)
Property improvements, fixtures and equipment	(54,187)	(37,407)	(21,750)
Office computers and furniture	(119)	(83)	(179)
Acquired real estate leases		(51,509)	(10,604)
Distributions in excess of earnings from non-consolidated REITs	1,396	1,023	107
Investment in related party mortgage loan receivable		(3,000)	(25,000)
Repayment of related party mortgage receivable	10,060	39,861
Proceeds received on sales of real estate assets	37,756	27,262	85,426
Net cash used in investing activities	(5,094)	(244,972)	(38,104)
Cash flows from financing activities:
Distributions to stockholders	(81,496)	(77,481)	(76,142)
Proceeds from equity offering		83,511
Offering costs		(609)
Borrowings under bank note payable	75,000	175,000	110,000
Repayments of bank note payable	(277,000)	(185,000)	(88,000)
Borrowing of Series A & Series B Senior Notes	200,000
Borrowing of term loan payable		150,000
Deferred financing costs	(6,902)	(3,647)
Net cash provided by (used in) financing activities	(90,398)	141,774	(54,142)
Net increase (decrease) in cash and cash equivalents	438	(8,828)	10,644
Cash and cash equivalents, beginning of year	9,335	18,163	7,519
Cash and cash equivalents, end of period	9,773	9,335	18,163
Cash paid for:
Interest	29,969	23,896	22,963
Taxes on income	584	490	803
Non-cash investing and financing activities:
Accrued costs for purchase of real estate assets	$ 5,140	$ 5,230	$ 3,211