Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended			18 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 22,060	$ (2,361)	$ 379,758	$ 34,565	$ 24,403
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Deferred rent and amortization of intangible assets, liabilities and lease inducements			(2,172)	(6,584)	(6,835)
Depreciation and amortization			58,364	71,968	72,361
Transfer of right to collect supplemental real estate tax reimbursements			(5,097)	0	0
Gain on sale of real estate	(23,005)	0	(401,737)	(39,666)	(3,092)
Impairment of real estate			13,100	0	0
Gain on disposition of assets held for sale			0	0	(5,151)
Straight line rent, below-market ground lease and amortization of intangible assets			1,069	1,766	1,899
Straight line lease termination income			(362)	0	0
Amortization of deferred loan costs			2,870	2,803	3,229
Amortization of premiums and discounts on debt			(590)	(870)	(1,179)
Unrealized premium adjustment			2,447	1,599	1,168
Amortization and accretion on loans receivable, net			96	(1,039)	(6,451)
Bad debt expense			677	161	1,428
Deferred income taxes			271	164	132
Stock-based compensation			154	164	971
Loans funded, held for sale to secondary market			(57,237)	(38,234)	(29,619)
Proceeds from sale of guaranteed loans			51,312	38,536	27,974
Principal collected on loans subject to secured borrowings			6,674	3,866	4,311
Other operating activity			(1,718)	136	(496)
Changes in operating assets and liabilities:
Accounts receivable and interest receivable			(977)	(2,569)	(350)
Other assets			(19,762)	419	(4,036)
Accounts payable and accrued expenses			(14,139)	630	3,678
Deferred leasing costs			(6,973)	(19,885)	(8,580)
Other liabilities			(5,589)	3,219	984
Due to related parties			(1,584)	724	286
Net cash (used in) provided by operating activities			(1,145)	51,873	77,035
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to investments in real estate			(21,101)	(35,414)	(26,614)
Acquisition of real estate properties			(19,631)	0	(11,143)
Proceeds from sale of real estate property, net			1,012,115	94,568	7,786
Proceeds from sale of assets held for sale, net			0	26,766	82,272
Loans funded			(19,079)	(66,001)	(29,848)
Principal collected on loans			10,883	33,470	39,950
Restricted cash			5,152	(25,150)	1,691
Other investing activity			317	1,287	178
Net cash provided by investing activities			968,656	29,526	64,272
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from mortgages payable			0	392,000	0
Payment of mortgages payable			(65,877)	(4,354)	(77,056)
Proceeds from unsecured revolving lines of credit, revolving credit facilities and term notes			120,000	175,000	619,000
Payment of unsecured revolving lines of credit, revolving credit facilities and term notes			(335,000)	(282,000)	(487,000)
Payment of principal on secured borrowings			(6,674)	(13,946)	(4,311)
Proceeds from secured borrowings			0	25,791	10,000
Payment of deferred preferred stock offering costs			(3,832)	(1,960)	0
Payment of deferred loan costs			(304)	(1,994)	(3,596)
Payment of common dividends			(38,327)	(77,316)	(85,389)
Payment of special cash dividends			(4,872)	0	0
Repurchase of Common Stock			(886,010)	(290,134)	0
Contributions from noncontrolling interests			0	0	110
Payment of borrowing costs			(8)	0	0
Net proceeds from issuance of Series A Preferred Warrants			127	5	0	$ 131
Payment of preferred stock dividends			(250)	0	0
Redemption of Series A Preferred Stock			(27)	0	0
Noncontrolling interests' distributions			(43)	(43)	(45)
Net cash used in financing activities			(982,650)	(77,522)	(28,287)
Change in cash balances included in assets held for sale			0	1,471	569
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS			(15,139)	5,348	113,589
CASH AND CASH EQUIVALENTS:
Beginning of period			144,449	139,101	25,512
End of period	129,310	144,449	129,310	144,449	139,101	129,310
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid during the period for interest			35,092	33,060	20,920
Federal income taxes paid			1,595	1,353	805
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Additions to investments in real estate included in accounts payable and accrued expenses			9,024	4,527	8,097
Retirement of treasury stock			0	0	4,901
Additions to investments in real estate included in other assets			0	0	4,244
Net increase (decrease) in fair value of derivatives applied to other comprehensive income (loss)			2,140	2,010	(2,519)
Foreclosure on a loan receivable included in other assets			0	0	708
Reduction of loans receivable and secured borrowings due to the SBA's repurchase of the guaranteed portion of loans			534	2,663	0
Additions to preferred stock offering costs included in accounts payable and accrued expenses			388	238	0
Accrual of dividends payable to preferred stockholders	249	9	249	9	0	249
Preferred stock offering costs offset against redeemable preferred stock in temporary equity			122	3	0
Preferred stock offering costs offset against redeemable preferred stock in permanent equity			2,532	0	0
Reclassification of Series A Preferred Stock from temporary equity to permanent equity			1,417	0	0
Reclassification of Series A Preferred Stock from temporary equity to accounts payable and accrued expenses			13	0	0
Accrual of special cash dividends	1,575	0	1,575	0	0	1,575
Accrual reversed to lease termination income			480	0	0
Payable to related parties included in net proceeds from disposition of real estate	$ 202	$ 0	202	0	0	$ 202
Series A Preferred Stock
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of Preferred Stock			28,070	1,429	0
Series L Preferred Stock
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of Preferred Stock			$ 210,377	$ 0	$ 0