SEGMENT REPORTING (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income Statement [Abstract]
Interest income	$ 72,763	$ 60,284	$ 196,410	$ 175,650
Interest expense	(42,607)	(30,685)	(109,625)	(88,622)
Net interest income	30,156	29,599	86,785	87,028
Provision for loan losses	0	0	0	(300)
Net interest income after provision for loan losses	30,156	29,599	86,785	86,728
Operating lease income	22,924	19,466	64,741	57,845
Tenant recoveries	2,382	1,185	5,121	3,844
Sale of loans, net	(775)	19,640	(1,774)	30,265
Realized gain on securities	6,688	7,126	19,182	9,524
Unrealized gain (loss) on Agency interest-only securities	577	(47)	1,034	29
Realized gain on sale of real estate, net	3,228	4,649	7,790	15,616
Fee and other income	4,338	8,101	13,378	17,258
Net result from derivative transactions	(348)	9,356	(18,352)	(66,148)
Earnings (loss) from investment in unconsolidated joint ventures	127	(141)	64	485
Gain (loss) on extinguishment of debt	0	0	(54)	5,382
Total other income	39,141	69,335	91,130	74,100
Salaries and employee benefits	(13,255)	(17,296)	(43,786)	(43,343)
Operating expenses	(4,790)	(4,391)	(16,098)	(15,399)
Real estate operating expenses	(9,351)	(8,392)	(24,861)	(23,244)
Fee expense	(1,242)	(803)	(3,556)	(2,407)
Depreciation and amortization	(10,606)	(9,733)	(29,323)	(28,789)
Total costs and expenses	(39,244)	(40,615)	(117,624)	(113,182)
Income tax (expense) benefit	400	(8,721)	3,224	(5,547)
Net income (loss)	30,453	49,598	63,515	42,099	$ 113,720
Total assets	6,412,040		6,412,040		5,578,337
Investment in unconsolidated joint ventures	35,007		35,007		34,025
Investment in FHLB stock	77,915		77,915		77,915
Operating Segment
Income Statement [Abstract]
Investment in unconsolidated joint ventures	35,000		35,000		34,000
Operating Segment | Loans
Income Statement [Abstract]
Interest income	63,417	40,639	161,738	117,516
Interest expense	(17,502)	(6,281)	(34,818)	(17,560)
Net interest income	45,915	34,358	126,920	99,956
Provision for loan losses	0	0	0	(300)
Net interest income after provision for loan losses	45,915	34,358	126,920	99,656
Operating lease income	0	0	0	0
Tenant recoveries	0	0	0	0
Sale of loans, net	(775)	19,640	(1,774)	30,265
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	(159)	0	0	0
Fee and other income	1,447	2,230	4,798	6,473
Net result from derivative transactions	990	4,656	(11,199)	(21,139)
Earnings (loss) from investment in unconsolidated joint ventures	0	0	0	0
Gain (loss) on extinguishment of debt			0	0
Total other income	1,503	26,526	(8,175)	15,599
Salaries and employee benefits	6,700	(3,300)	0	(6,300)
Operating expenses	99	0	212	0
Real estate operating expenses	0	0	0	0
Fee expense	(992)	(1,077)	(2,798)	(1,501)
Depreciation and amortization	0	0	0	0
Total costs and expenses	5,807	(4,377)	(2,586)	(7,801)
Income tax (expense) benefit	0	0	0	0
Net income (loss)	53,225	56,507	116,159	107,454
Total assets	3,964,426		3,964,426		2,353,977
Operating Segment | Securities
Income Statement [Abstract]
Interest income	9,263	19,630	34,532	58,088
Interest expense	(1,456)	(2,902)	(5,179)	(7,039)
Net interest income	7,807	16,728	29,353	51,049
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	7,807	16,728	29,353	51,049
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	6,688	7,126	19,182	9,524
Unrealized gain (loss) on Agency interest-only securities	577	(47)	1,034	29
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	(1,338)	4,700	(7,153)	(45,009)
Earnings (loss) from investment in unconsolidated joint ventures	0	0	0	0
Gain (loss) on extinguishment of debt			0	0
Total other income	5,927	11,779	13,063	(35,456)
Salaries and employee benefits	0	0	0	0
Operating expenses	0	0	0	0
Real estate operating expenses	0	0	0	0
Fee expense	(68)	(15)	(230)	(33)
Depreciation and amortization	0	0	0	0
Total costs and expenses	(68)	(15)	(230)	(33)
Income tax (expense) benefit	0	0	0	0
Net income (loss)	13,666	28,492	42,186	15,560
Total assets	1,098,471		1,098,471		2,100,947
Operating Segment | Real Estate
Income Statement [Abstract]
Interest income	3	4	9	5
Interest expense	(6,785)	(6,276)	(19,709)	(18,675)
Net interest income	(6,782)	(6,272)	(19,700)	(18,670)
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	(6,782)	(6,272)	(19,700)	(18,670)
Operating lease income	22,924	19,466	64,741	57,845
Tenant recoveries	2,382	1,185	5,121	3,844
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	3,387	4,649	7,790	15,616
Fee and other income	2,057	1,867	6,040	5,129
Net result from derivative transactions	0	0	0	0
Earnings (loss) from investment in unconsolidated joint ventures	127	(141)	64	(407)
Gain (loss) on extinguishment of debt			0	0
Total other income	30,877	27,026	83,756	82,027
Salaries and employee benefits	0	0	0	0
Operating expenses	0	0	0	(1)
Real estate operating expenses	(9,351)	(8,392)	(24,861)	(23,244)
Fee expense	(182)	(151)	(528)	(389)
Depreciation and amortization	(10,583)	(9,705)	(29,253)	(28,704)
Total costs and expenses	(20,116)	(18,248)	(54,642)	(52,338)
Income tax (expense) benefit	0	0	0	0
Net income (loss)	3,979	2,506	9,414	11,019
Total assets	1,076,908		1,076,908		856,363
Corporate/Other
Income Statement [Abstract]
Interest income	80	11	131	41
Interest expense	(16,864)	(15,226)	(49,919)	(45,348)
Net interest income	(16,784)	(15,215)	(49,788)	(45,307)
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	(16,784)	(15,215)	(49,788)	(45,307)
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	834	4,004	2,540	5,656
Net result from derivative transactions	0	0	0	0
Earnings (loss) from investment in unconsolidated joint ventures	0	0	0	892
Gain (loss) on extinguishment of debt			(54)	5,382
Total other income	834	4,004	2,486	11,930
Salaries and employee benefits	(19,955)	(13,996)	(43,786)	(37,043)
Operating expenses	(4,889)	(4,391)	(16,310)	(15,398)
Real estate operating expenses	0	0		0
Fee expense	0	440	0	(484)
Depreciation and amortization	(23)	(28)	(70)	(85)
Total costs and expenses	(24,867)	(17,975)	(60,166)	(53,010)
Income tax (expense) benefit	400	(8,721)	3,224	(5,547)
Net income (loss)	(40,417)	$ (37,907)	(104,244)	$ (91,934)
Total assets	272,235		272,235		267,050
Investment in FHLB stock	77,900		77,900		77,900
Deferred tax assets	6,700		6,700		2,100
Corporate/Other | Senior Unsecured Notes
Income Statement [Abstract]
Senior Notes	$ 1,200,000		$ 1,200,000		$ 559,800