SEGMENT REPORTING (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) segment	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
SEGMENT REPORTING
Number of reportable segments | segment			3
Interest income	$ 55,766,000	$ 59,239,000	$ 115,366,000	$ 115,622,000
Interest expense	(28,402,000)	(27,487,000)	(57,938,000)	(54,311,000)
Net interest income (expense)	27,364,000	31,752,000	57,428,000	61,311,000
Provision for loan losses	(150,000)	(150,000)	(300,000)	(300,000)
Net interest income after provision for loan losses	27,214,000	31,602,000	57,128,000	61,011,000
Operating lease income	19,085,000	20,390,000	38,379,000	39,537,000
Tenant recoveries	1,324,000	2,510,000	2,659,000	5,036,000
Sale of loans, net	2,795,000	14,524,000	10,625,000	44,551,000
Realized gain on securities	2,971,000	11,017,000	2,398,000	23,167,000
Unrealized gain (loss) on Agency interest-only securities	(584,000)	(51,000)	76,000	(1,369,000)
Realized gain on sale of real estate, net	4,873,000	7,278,000	10,968,000	14,940,000
Fee and other income	6,181,000	3,833,000	9,156,000	7,374,000
Net result from derivative transactions	(24,642,000)	26,787,000	(75,504,000)	(12,352,000)
Earnings from investment in unconsolidated joint ventures	(168,000)	164,000	626,000	605,000
Gain on extinguishment of debt	0	0	5,382,000	0
Total other income (loss)	11,835,000	86,452,000	4,765,000	121,489,000
Salaries and employee benefits	(13,432,000)	(15,947,000)	(26,047,000)	(29,705,000)
Operating expenses	(4,713,000)	(6,734,000)	(11,008,000)	(15,537,000)
Real estate operating expenses	(8,925,000)	(9,628,000)	(14,644,000)	(19,001,000)
Real estate acquisition costs	(208,000)	(454,000)	(208,000)	(1,054,000)
Fee expense	(873,000)	(1,463,000)	(1,603,000)	(2,585,000)
Depreciation and amortization	(9,254,000)	(9,954,000)	(19,057,000)	(19,677,000)
Total costs and expenses	(37,405,000)	(44,180,000)	(72,567,000)	(87,559,000)
Tax (expense) benefit	2,301,000	(5,177,000)	3,174,000	(8,282,000)
Net income (loss)	3,945,000	68,697,000	(7,500,000)	86,659,000
Total assets	5,987,373,000		5,987,373,000		$ 5,895,212,000
Investment in unconsolidated joint ventures	33,778,000		33,778,000		33,797,000
Investment in FHLB stock	77,915,000		77,915,000		77,915,000
Senior Unsecured Notes | Various Dates
SEGMENT REPORTING
Senior Notes	558,700,000		558,700,000
LCRIP I
SEGMENT REPORTING
Fee and other income	0	14,964	6,905	77,447
Earnings from investment in unconsolidated joint ventures	0	14,000	892,000	116,000
Investment in unconsolidated joint ventures	0		0		49,000
Operating Segment | Real Estate Joint Ventures
SEGMENT REPORTING
Investment in unconsolidated joint ventures	33,800,000		33,800,000		33,700,000
Operating Segment | Loans
SEGMENT REPORTING
Interest income	35,549,000	39,680,000	76,877,000	75,737,000
Interest expense	(5,128,000)	(5,337,000)	(11,279,000)	(10,759,000)
Net interest income (expense)	30,421,000	34,343,000	65,598,000	64,978,000
Provision for loan losses	(150,000)	(150,000)	(300,000)	(300,000)
Net interest income after provision for loan losses	30,271,000	34,193,000	65,298,000	64,678,000
Operating lease income	0	0	0	0
Tenant recoveries	0	0	0	0
Sale of loans, net	2,795,000	14,524,000	10,625,000	44,551,000
Realized gain on securities	0	0	0	0
Unrealized gain (loss) on Agency interest-only securities	0	0	0	0
Realized gain on sale of real estate, net	(800,000)	641,000	(159,000)	1,252,000
Fee and other income	2,438,000	1,601,000	4,243,000	3,085,000
Net result from derivative transactions	(9,670,000)	8,774,000	(25,795,000)	(5,176,000)
Earnings from investment in unconsolidated joint ventures	0	0	0	0
Gain on extinguishment of debt			0
Total other income (loss)	(5,237,000)	25,540,000	(11,086,000)	43,712,000
Salaries and employee benefits	(1,500,000)	(4,111,000)	(3,000,000)	(6,911,000)
Operating expenses	0	100,000	0	169,000
Real estate operating expenses	0	0	0	0
Real estate acquisition costs	0	0	0	0
Fee expense	12,000	(907,000)	(424,000)	(1,798,000)
Depreciation and amortization	0	0	0	0
Total costs and expenses	(1,488,000)	(4,918,000)	(3,424,000)	(8,540,000)
Tax (expense) benefit	0	0	0	0
Net income (loss)	23,546,000	54,815,000	50,788,000	99,850,000
Total assets	2,127,336,000		2,127,336,000		2,310,409,000
Operating Segment | Securities
SEGMENT REPORTING
Interest income	20,202,000	19,528,000	38,458,000	39,848,000
Interest expense	(2,167,000)	(1,748,000)	(4,137,000)	(3,760,000)
Net interest income (expense)	18,035,000	17,780,000	34,321,000	36,088,000
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	18,035,000	17,780,000	34,321,000	36,088,000
Operating lease income	0	0	0	0
Tenant recoveries	0	0	0	0
Sale of loans, net	0	0	0	0
Realized gain on securities	2,971,000	11,017,000	2,398,000	23,167,000
Unrealized gain (loss) on Agency interest-only securities	(584,000)	(51,000)	76,000	(1,369,000)
Realized gain on sale of real estate, net	0	0	0	0
Fee and other income	0	0	0	0
Net result from derivative transactions	(14,972,000)	18,013,000	(49,709,000)	(7,176,000)
Earnings from investment in unconsolidated joint ventures	0	0	0	0
Gain on extinguishment of debt			0
Total other income (loss)	(12,585,000)	28,979,000	(47,235,000)	14,622,000
Salaries and employee benefits	0	0	0	0
Operating expenses	0	0	0	0
Real estate operating expenses	0	0	0	0
Real estate acquisition costs	0	0	0	0
Fee expense	(17,000)	(20,000)	(17,000)	(21,000)
Depreciation and amortization	0	0	0	0
Total costs and expenses	(17,000)	(20,000)	(17,000)	(21,000)
Tax (expense) benefit	0	0	0	0
Net income (loss)	5,433,000	46,739,000	(12,931,000)	50,689,000
Total assets	2,700,210,000		2,700,210,000		2,407,217,000
Operating Segment | Real Estate
SEGMENT REPORTING
Interest income	2,000	0	2,000	0
Interest expense	(6,204,000)	(6,086,000)	(12,399,000)	(11,305,000)
Net interest income (expense)	(6,202,000)	(6,086,000)	(12,397,000)	(11,305,000)
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	(6,202,000)	(6,086,000)	(12,397,000)	(11,305,000)
Operating lease income	19,085,000	20,390,000	38,379,000	39,537,000
Tenant recoveries	1,324,000	2,510,000	2,659,000	5,036,000
Sale of loans, net	0	0	0	0
Realized gain on securities	0	0	0	0
Unrealized gain (loss) on Agency interest-only securities	0	0	0	0
Realized gain on sale of real estate, net	5,673,000	6,637,000	11,127,000	13,688,000
Fee and other income	2,920,000	17,000	3,262,000	27,000
Net result from derivative transactions	0	0	0	0
Earnings from investment in unconsolidated joint ventures	(168,000)	150,000	(266,000)	489,000
Gain on extinguishment of debt			0
Total other income (loss)	28,834,000	29,704,000	55,161,000	58,777,000
Salaries and employee benefits	0	0	0	0
Operating expenses	421,000	0	(1,000)	0
Real estate operating expenses	(8,925,000)	(9,628,000)	(14,644,000)	(19,001,000)
Real estate acquisition costs	(208,000)	(454,000)	(208,000)	(1,054,000)
Fee expense	(124,000)	(69,000)	(237,000)	(107,000)
Depreciation and amortization	(9,213,000)	(9,908,000)	(19,010,000)	(19,626,000)
Total costs and expenses	(18,049,000)	(20,059,000)	(34,100,000)	(39,788,000)
Tax (expense) benefit	0	0	0	0
Net income (loss)	4,583,000	3,559,000	8,664,000	7,684,000
Total assets	842,533,000		842,533,000		868,528,000
Corporate/Other
SEGMENT REPORTING
Interest income	13,000	31,000	29,000	37,000
Interest expense	(14,903,000)	(14,316,000)	(30,123,000)	(28,487,000)
Net interest income (expense)	(14,890,000)	(14,285,000)	(30,094,000)	(28,450,000)
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	(14,890,000)	(14,285,000)	(30,094,000)	(28,450,000)
Operating lease income	0	0	0	0
Tenant recoveries	0	0	0	0
Sale of loans, net	0	0	0	0
Realized gain on securities	0	0	0	0
Unrealized gain (loss) on Agency interest-only securities	0	0	0	0
Realized gain on sale of real estate, net	0	0	0	0
Fee and other income	823,000	2,215,000	1,651,000	4,262,000
Net result from derivative transactions	0	0	0	0
Earnings from investment in unconsolidated joint ventures	0	14,000	892,000	116,000
Gain on extinguishment of debt			5,382,000
Total other income (loss)	823,000	2,229,000	7,925,000	4,378,000
Salaries and employee benefits	(11,932,000)	(11,836,000)	(23,047,000)	(22,794,000)
Operating expenses	(5,134,000)	(6,834,000)	(11,007,000)	(15,706,000)
Real estate operating expenses	0	0	0	0
Real estate acquisition costs	0	0	0	0
Fee expense	(744,000)	(467,000)	(925,000)	(659,000)
Depreciation and amortization	(41,000)	(46,000)	(47,000)	(51,000)
Total costs and expenses	(17,851,000)	(19,183,000)	(35,026,000)	(39,210,000)
Tax (expense) benefit	2,301,000	(5,177,000)	3,174,000	(8,282,000)
Net income (loss)	(29,617,000)	$ (36,416,000)	(54,021,000)	$ (71,564,000)
Total assets	317,294,000		317,294,000		309,058,000
Investment in FHLB stock	77,900,000		77,900,000		77,900,000
Deferred tax assets	10,900,000		10,900,000		5,000,000
Corporate/Other | Senior Unsecured Notes | Various Dates
SEGMENT REPORTING
Senior Notes	$ 558,700,000		$ 558,700,000		612,600,000
Corporate/Other | LCRIP I
SEGMENT REPORTING
Investment in unconsolidated joint ventures					$ 48,771