Segment Reporting (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Net interest margin		$ 14,394	$ 16,525	$ 30,876	$ 32,859
Property income		67,898	55,534	136,620	108,808
Fee and other income		2,775	7,629	5,627	13,223
Provision for losses		1,344	2,000	2,669	4,000
Depreciation and amortization expense		22,806	17,007	47,082	36,031
Operating income		(5,659)	1,760	(11,899)	(1,487)
Change in fair value of financial instruments		(1,592)	8,356	(5,680)	12,846
Income tax benefit (provision)		1,756	(715)	2,749	(1,297)
Net income (loss)		26,405	26,441	15,902	26,707
Operating Segments | Owning and Management Segment
Segment Reporting Information [Line Items]
Net interest margin		14,490	16,766	31,237	33,338
Property income		29,571	32,816	59,627	64,433
Fee and other income		9,834	12,049	19,559	21,839
Provision for losses		1,344	2,000	2,669	4,000
Depreciation and amortization expense		15,171	11,287	27,920	24,273
Operating income		(7,686)	1,406	(11,336)	(1,598)
Change in fair value of financial instruments		(1,592)	8,356	(5,680)	12,846
Income tax benefit (provision)		1,756	(715)	2,749	(1,297)
Net income (loss)		64	27,396	(10,405)	29,213
Operating Segments | IRT Segment
Segment Reporting Information [Line Items]
Property income		38,327	22,718	76,993	44,375
Depreciation and amortization expense		7,635	5,720	19,162	11,758
Operating income		2,027	353	(563)	111
Net income (loss)		30,790	353	30,744	112
Eliminations
Segment Reporting Information [Line Items]
Net interest margin	[1]	(96)	(241)	(361)	(479)
Fee and other income	[1]	(7,059)	(4,420)	(13,932)	(8,616)
Operating income	[1]		1
Net income (loss)	[1]	$ (4,449)	$ (1,308)	$ (4,437)	$ (2,618)

[1] The transactions that occur between the reportable segments include advisory and property management services, as well as providing commercial mortgages on our owned real estate.