SEGMENT REPORTING (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
SEGMENT REPORTING
Number of reportable segments | segment									3
Interest income	$ 62,903,000	$ 63,013,000	$ 59,239,000	$ 56,384,000	$ 56,931,000	$ 48,459,000	$ 45,112,000	$ 36,822,000	$ 241,539,000	$ 187,325,000	$ 121,578,000
Interest expense									(113,303,000)	(77,574,000)	(48,745,000)
Net interest income									128,236,000	109,751,000	72,833,000
Provision for loan losses									(600,000)	(600,000)	(600,000)
Net interest income after provision for loan losses	33,297,000	33,328,000	31,602,000	29,409,000	30,728,000	28,381,000	28,211,000	21,831,000	127,636,000	109,151,000	72,233,000
Operating lease income									80,465,000	56,649,000	37,395,000
Tenant recoveries									9,907,000	9,183,000	3,271,000
Sale of loans, net									71,066,000	145,275,000	146,708,000
Realized gain on securities									24,007,000	26,977,000	4,231,000
Unrealized gain (loss) on Agency interest-only securities									(1,249,000)	2,144,000	(2,665,000)
Realized gain on sale of real estate, net									40,386,000	29,760,000	13,565,000
Fee and other income									15,205,000	11,704,000	7,922,000
Net result from derivative transactions									(38,937,000)	(94,798,000)	28,075,000
Earnings (loss) from investment in unconsolidated joint ventures									371,000	1,990,000	3,203,000
Gain on assignment of mortgage loan financing									0	432,000	0
Loss on extinguishment of debt									0	(150,000)	0
Other income	72,183,000	7,549,000	86,452,000	35,037,000	31,906,000	61,337,000	55,489,000	40,434,000	201,221,000	189,166,000	241,705,000
Salaries and employee benefits									(61,612,000)	(82,144,000)	(61,038,000)
Operating expenses									(25,103,000)	(25,398,000)	(14,937,000)
Real estate operating expenses									(35,886,000)	(32,670,000)	(17,404,000)
Real estate acquisition costs									(1,983,000)	(2,404,000)	(3,626,000)
Fee expense									(4,521,000)	(3,023,000)	(2,955,000)
Depreciation and amortization									(39,061,000)	(28,447,000)	(21,515,000)
Total costs and expenses	(38,347,000)	(42,260,000)	(44,180,000)	(43,379,000)	(48,045,000)	(42,207,000)	(45,258,000)	(38,575,000)	(168,166,000)	(174,086,000)	(121,475,000)
Tax (expense) benefit	(10,457,000)	4,181,000	(5,177,000)	(3,104,000)	(2,783,000)	(10,335,000)	(8,199,000)	(5,289,000)	(14,557,000)	(26,605,000)	(3,730,000)
Net income	56,676,000	$ 2,798,000	$ 68,697,000	$ 17,963,000	11,806,000	$ 37,176,000	$ 30,243,000	$ 18,401,000	146,134,000	97,626,000	188,733,000
Total assets	5,895,212,000				5,814,235,000				5,895,212,000	5,814,235,000	3,482,216,000
Company’s investment in unconsolidated joint ventures	33,797,000				6,041,000				33,797,000	6,041,000
Investment in FHLB stock	77,915,000				72,340,000				77,915,000	72,340,000
Deferred tax assets	5,000,000				8,200,000				5,000,000	8,200,000
Operating Segment | Loans
SEGMENT REPORTING
Interest income									165,403,000	113,943,000	63,894,000
Interest expense									(24,039,000)	(13,205,000)	(4,592,000)
Net interest income									141,364,000	100,738,000	59,302,000
Provision for loan losses									(600,000)	(600,000)	(600,000)
Net interest income after provision for loan losses									140,764,000	100,138,000	58,702,000
Operating lease income									0	0	0
Tenant recoveries									0	0	0
Sale of loans, net									71,066,000	145,275,000	146,708,000
Realized gain on securities									0	0	0
Unrealized gain (loss) on Agency interest-only securities									0	0	0
Realized gain on sale of real estate, net									2,346,000	1,525,000	0
Fee and other income									5,999,000	3,854,000	2,963,000
Net result from derivative transactions									(12,609,000)	(34,599,000)	15,836,000
Earnings (loss) from investment in unconsolidated joint ventures									0	0	0
Gain on assignment of mortgage loan financing										0
Loss on extinguishment of debt										0
Other income									66,802,000	116,055,000	165,507,000
Salaries and employee benefits									(16,531,000)	(22,400,000)	(26,250,000)
Operating expenses									381,000	235,000	201,000
Real estate operating expenses									0	0	0
Real estate acquisition costs									0	0	0
Fee expense									(1,693,000)	(2,172,000)	(1,981,000)
Depreciation and amortization									0	0	0
Total costs and expenses									(17,843,000)	(24,337,000)	(28,030,000)
Tax (expense) benefit									0	0	0
Net income									189,723,000	191,856,000	196,179,000
Total assets	2,310,409,000				1,939,008,000				2,310,409,000	1,939,008,000	979,568,000
Operating Segment | Securities
SEGMENT REPORTING
Interest income									76,083,000	73,331,000	57,636,000
Interest expense									(7,256,000)	(6,588,000)	(3,289,000)
Net interest income									68,827,000	66,743,000	54,347,000
Provision for loan losses									0	0	0
Net interest income after provision for loan losses									68,827,000	66,743,000	54,347,000
Operating lease income									0	0	0
Tenant recoveries									0	0	0
Sale of loans, net									0	0	0
Realized gain on securities									24,007,000	26,977,000	4,231,000
Unrealized gain (loss) on Agency interest-only securities									(1,249,000)	2,144,000	(2,665,000)
Realized gain on sale of real estate, net									0	0	0
Fee and other income									230,000	0	195,000
Net result from derivative transactions									(26,328,000)	(60,199,000)	12,239,000
Earnings (loss) from investment in unconsolidated joint ventures									0	0	0
Gain on assignment of mortgage loan financing										0
Loss on extinguishment of debt										0
Other income									(3,340,000)	(31,078,000)	14,000,000
Salaries and employee benefits									0	0	0
Operating expenses									0	0	0
Real estate operating expenses									0	0	0
Real estate acquisition costs									0	0	0
Fee expense									(40,000)	(65,000)	(375,000)
Depreciation and amortization									0	0	0
Total costs and expenses									(40,000)	(65,000)	(375,000)
Tax (expense) benefit									0	0	0
Net income									65,447,000	35,600,000	67,972,000
Total assets	2,407,217,000				2,815,566,000				2,407,217,000	2,815,566,000	1,657,246,000
Operating Segment | Real Estate
SEGMENT REPORTING
Interest income									0	0	0
Interest expense									(23,873,000)	(15,984,000)	(7,673,000)
Net interest income									(23,873,000)	(15,984,000)	(7,673,000)
Provision for loan losses									0	0	0
Net interest income after provision for loan losses									(23,873,000)	(15,984,000)	(7,673,000)
Operating lease income									80,465,000	56,649,000	37,395,000
Tenant recoveries									9,907,000	9,183,000	3,271,000
Sale of loans, net									0	0	0
Realized gain on securities									0	0	0
Unrealized gain (loss) on Agency interest-only securities									0	0	0
Realized gain on sale of real estate, net									38,040,000	28,235,000	13,565,000
Fee and other income									5,989,000	5,374,000	312,000
Net result from derivative transactions									0	0	0
Earnings (loss) from investment in unconsolidated joint ventures									255,000	900,000	0
Gain on assignment of mortgage loan financing										432,000
Loss on extinguishment of debt										0
Other income									134,656,000	100,773,000	54,543,000
Salaries and employee benefits									0	0	0
Operating expenses									0	0	(7,000)
Real estate operating expenses									(35,886,000)	(32,670,000)	(17,404,000)
Real estate acquisition costs									(1,982,000)	(2,400,000)	(3,626,000)
Fee expense									(470,000)	(83,000)	(33,000)
Depreciation and amortization									(38,953,000)	(28,271,000)	(20,968,000)
Total costs and expenses									(77,291,000)	(63,424,000)	(42,038,000)
Tax (expense) benefit									0	0	0
Net income									33,492,000	21,365,000	4,832,000
Total assets	868,528,000				771,129,000				868,528,000	771,129,000	626,362,000
Corporate / Other
SEGMENT REPORTING
Interest income									53,000	51,000	48,000
Interest expense									(58,135,000)	(41,797,000)	(33,191,000)
Net interest income									(58,082,000)	(41,746,000)	(33,143,000)
Provision for loan losses									0	0	0
Net interest income after provision for loan losses									(58,082,000)	(41,746,000)	(33,143,000)
Operating lease income									0	0	0
Tenant recoveries									0	0	0
Sale of loans, net									0	0	0
Realized gain on securities									0	0	0
Unrealized gain (loss) on Agency interest-only securities									0	0	0
Realized gain on sale of real estate, net									0	0	0
Fee and other income									2,987,000	2,476,000	4,452,000
Net result from derivative transactions									0	0	0
Earnings (loss) from investment in unconsolidated joint ventures									116,000	1,090,000	3,203,000
Gain on assignment of mortgage loan financing										0
Loss on extinguishment of debt										(150,000)
Other income									3,103,000	3,416,000	7,655,000
Salaries and employee benefits									(45,081,000)	(59,744,000)	(34,788,000)
Operating expenses									(25,484,000)	(25,633,000)	(15,131,000)
Real estate operating expenses									0	0	0
Real estate acquisition costs									(1,000)	(4,000)	0
Fee expense									(2,318,000)	(703,000)	(566,000)
Depreciation and amortization									(108,000)	(176,000)	(547,000)
Total costs and expenses									(72,992,000)	(86,260,000)	(51,032,000)
Tax (expense) benefit									(14,557,000)	(26,605,000)	(3,730,000)
Net income									(142,528,000)	(151,195,000)	(80,250,000)
Total assets	309,058,000				288,532,000				309,058,000	288,532,000	219,040,000
LCRIP I
SEGMENT REPORTING
Fee and other income									77,400	400,000	800,000
Earnings (loss) from investment in unconsolidated joint ventures									116,000	1,090,000	$ 2,568,000
Company’s investment in unconsolidated joint ventures	48,771				3,898,000				48,771	3,898,000
Real Estate Joint Ventures
SEGMENT REPORTING
Company’s investment in unconsolidated joint ventures	33,700,000				2,100,000				33,700,000	2,100,000
Senior Unsecured Notes | Various Dates
SEGMENT REPORTING
Senior Notes	$ 612,605,000				$ 610,129,000				$ 612,605,000	$ 610,129,000