QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
QUARTERLY FINANCIAL INFORMATION (UNAUDITED)
Revenues from continuing operations	$ 52,744	$ 55,384	$ 61,299	$ 66,949	$ 64,622	$ 64,332	$ 68,360	$ 68,617	$ 236,376	$ 265,931	$ 276,948
Gain on sale of real estate	23,005	74,715	116,283	187,734	0	14,927	0	24,739	401,737	39,666	3,092
Net income (loss) from continuing operations	22,060	72,391	91,372	193,935	(3,153)	8,382	(810)	26,293	379,758	30,712	6,112
Net income from discontinued operations					792	703	1,668	690	0	3,853	18,291
Net income (loss)	22,060	72,391	91,372	193,935	(2,361)	9,085	858	26,983	379,758	34,565	24,403
Net income (loss) attributable to the Company	22,049	72,395	91,363	193,930	(2,370)	9,088	849	26,980	379,737	34,547	24,392
Redeemable preferred stock dividends declared	(249)	(138)	(72)	(31)	(9)	0	0	0	(490)	(9)	0
Redeemable preferred stock redemptions	2	0	0	0					2	0	0
Net income (loss) available to common stockholders	$ 21,802	$ 72,257	$ 91,291	$ 193,899	$ (2,379)	$ 9,088	$ 849	$ 26,980	$ 379,249	$ 34,538	$ 24,392
BASIC AND DILUTED NET INCOME AVAILABLE TO COMMON STOCKHOLDERS PER SHARE (1):
Continuing operations (in usd per share)	$ 0.36	$ 1.25	$ 1.16	$ 2.31	$ (0.04)	$ 0.10	$ (0.01)	$ 0.27	$ 5.47	$ 0.34	$ 0.06
Discontinued operations (in usd per share)					0.01	0.01	0.02	0.01	0.00	0.04	0.19
Net income (in usd per share)	$ 0.36	$ 1.25	$ 1.16	$ 2.31	$ (0.03)	$ 0.10	$ 0.01	$ 0.28	$ 5.47	$ 0.38	$ 0.25
Weighted average shares of Common Stock outstanding - basic (in shares)	55,885	57,876	78,871	84,048	84,048	87,045	96,683	97,662	69,062	91,328	97,588
Weighted average shares of Common Stock outstanding - diluted (in shares)	55,917	57,876	78,871	84,048	84,048	87,045	96,683	97,662	69,070	91,328	97,588