Indebtedness - Additional Information (Detail)					3 Months Ended			6 Months Ended			12 Months Ended
		Jun. 30, 2017 USD ($) $ / shares		Jun. 23, 2017 USD ($)	Jun. 30, 2017 USD ($) $ / shares		Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Property $ / shares		Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)		May 31, 2017 USD ($)	Apr. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Jan. 31, 2017 USD ($)	Jan. 01, 2017 USD ($)	Jul. 31, 2016 USD ($)
Debt Instrument [Line Items]
Unpaid Principal Balance		$ 1,618,704,000			$ 1,618,704,000			$ 1,618,704,000			$ 1,787,974,000
Gains (losses) on extinguishments of debt					(1,598,000)		$ 660,000	1,588,000		$ 1,004,000
Non-cash loss on deconsolidation of properties								(15,947,000)
Industrial real estate properties
Debt Instrument [Line Items]
Non-cash loss on deconsolidation of properties								$ (15,947,000)
Number of industrial real estate properties deconsolidated | Property								10
Deconsolidation of properties, carrying value		$ 38,516,000			38,516,000			$ 38,516,000			82,501,000
Number of mortgage liens properties | Property								5
Mortgage liens properties aggregate carrying value								$ 43,414,000
Extinguishment of debt								$ 27,467,000
Remaining number of industrial real estate properties | Property								5
R A I T F L Seven
Debt Instrument [Line Items]
Contractual Maturity, month and year		2037-06
R A I T F L Seven | London Interest Bank Offer Rate
Debt Instrument [Line Items]
Interest rate at LIBOR plus basis rate				1.44%
R A I T F L Seven | Junior Notes
Debt Instrument [Line Items]
Owned unrated classes of junior notes				$ 65,479,000
CMBS securitizations | R A I T F L Seven
Debt Instrument [Line Items]
Real estate investment		$ 342,373,000		342,373,000	342,373,000			$ 342,373,000
Recourse Indebtedness
Debt Instrument [Line Items]
Unpaid Principal Balance		344,966,000			344,966,000			344,966,000			$ 387,179,000
Recourse Indebtedness | Seventy Five Thousand CMF [Member] | Secured warehouse facilities
Debt Instrument [Line Items]
Unpaid Principal Balance		13,068,000			13,068,000			13,068,000
Line of credit facility, borrowing capacity		75,000,000			75,000,000			$ 75,000,000
Debt instrument, financial covenant compliance								As of June 30, 2017, we were in compliance with all financial covenants contained in the $75,000 commercial mortgage facility.
Recourse Indebtedness | One Hundred Fifty Thousand CMF Two [Member] | Secured warehouse facilities
Debt Instrument [Line Items]
Unpaid Principal Balance		0			0			$ 0
Line of credit facility, borrowing capacity		$ 250,000,000			$ 250,000,000			$ 250,000,000					$ 150,000,000
Debt instrument, financial covenant compliance								As of June 30, 2017, we were in compliance with all financial covenants contained in the $250,000 commercial mortgage facility.
Recourse Indebtedness | 7.0% convertible senior notes
Debt Instrument [Line Items]
Stated interest rate		7.00%			7.00%			7.00%			7.00%
Convertible note conversion rate								195.0060
Principal amount of convertible note, conversion rate		$ 1,000			$ 1,000			$ 1,000
Initial conversion price | $ / shares		$ 5.13			$ 5.13			$ 5.13
Unpaid Principal Balance	[1]	$ 871,000			$ 871,000			$ 871,000			$ 871,000
Contractual Maturity, month and year	[1]							2031-04			2031-04
Recourse Indebtedness | 4.0% convertible senior notes
Debt Instrument [Line Items]
Stated interest rate		4.00%			4.00%			4.00%			4.00%
Convertible note conversion rate								108.5803
Principal amount of convertible note, conversion rate		$ 1,000			$ 1,000			$ 1,000
Initial conversion price | $ / shares		$ 9.21			$ 9.21			$ 9.21
Unpaid Principal Balance	[2]	$ 126,098,000			$ 126,098,000			$ 126,098,000			$ 126,098,000
Contractual Maturity, month and year	[2]							2033-10			2033-10
Recourse Indebtedness | 7.625% senior notes due 2024
Debt Instrument [Line Items]
Stated interest rate		7.625%			7.625%			7.625%
Unpaid Principal Balance		$ 57,287,000			$ 57,287,000			$ 57,287,000			$ 57,287,000
Convenant leverage ratio		77.60%			77.60%			77.60%
Convenant fixed charge coverage ratio		274.00%			274.00%			274.00%
Contractual Maturity, month and year								2024-04			2024-04
Recourse Indebtedness | 7.625% senior notes due 2024 | Maximum
Debt Instrument [Line Items]
Convenant leverage ratio		80.00%			80.00%			80.00%
Recourse Indebtedness | 7.625% senior notes due 2024 | Minimum
Debt Instrument [Line Items]
Convenant fixed charge coverage ratio		120.00%			120.00%			120.00%
Recourse Indebtedness | 7.125% Senior Notes due 2019
Debt Instrument [Line Items]
Stated interest rate		7.125%			7.125%			7.125%
Unpaid Principal Balance		$ 70,731,000			$ 70,731,000			$ 70,731,000			$ 70,731,000
Convenant leverage ratio		77.60%			77.60%			77.60%
Convenant fixed charge coverage ratio		274.00%			274.00%			274.00%
Contractual Maturity, month and year								2019-08			2019-08
Recourse Indebtedness | 7.125% Senior Notes due 2019 | Maximum
Debt Instrument [Line Items]
Convenant leverage ratio		80.00%			80.00%			80.00%
Recourse Indebtedness | 7.125% Senior Notes due 2019 | Minimum
Debt Instrument [Line Items]
Convenant fixed charge coverage ratio		120.00%			120.00%			120.00%
Recourse Indebtedness | Senior Secured Notes
Debt Instrument [Line Items]
Unpaid Principal Balance		$ 15,500,000			$ 15,500,000			$ 15,500,000			$ 62,000,000
Payment of notes								$ 3,500,000
Recourse Indebtedness | Senior Secured Notes | Maximum
Debt Instrument [Line Items]
Contractual Maturity, month and year								2019-04			2019-04
Recourse Indebtedness | Senior Secured Notes | Minimum
Debt Instrument [Line Items]
Contractual Maturity, month and year								2018-10			2017-04
Recourse Indebtedness | 6.75% Senior Notes
Debt Instrument [Line Items]
Debt instrument redemption amount																$ 15,500,000
Recourse Indebtedness | 6.85% Senior Notes
Debt Instrument [Line Items]
Debt instrument redemption amount															$ 15,000,000
Recourse Indebtedness | 7.15% Senior Notes
Debt Instrument [Line Items]
Debt instrument redemption amount		2,500,000			2,500,000			$ 2,500,000						$ 10,000,000
Recourse Indebtedness | Junior subordinated notes, at fair value
Debt Instrument [Line Items]
Aggregate principal amount of notes issued		18,671,000			18,671,000			18,671,000
Fair value of indebtedness		12,524,000			12,524,000			12,524,000
Recourse Indebtedness | Secured warehouse facilities
Debt Instrument [Line Items]
Unpaid Principal Balance		30,708,000			30,708,000			30,708,000			$ 26,421,000
Recourse Indebtedness | Secured warehouse facilities | CMBS Borrowings
Debt Instrument [Line Items]
Unpaid Principal Balance		0			0			0
Recourse Indebtedness | Secured warehouse facilities | Commercial mortgage loans
Debt Instrument [Line Items]
Unpaid Principal Balance		17,640,000			17,640,000			17,640,000
Line of credit facility, borrowing capacity		200,000,000			200,000,000			$ 200,000,000										$ 150,000,000
Extended maturity term								Jul. 28, 2018
Recourse Indebtedness | Secured warehouse facilities | Floating Rate Loans
Debt Instrument [Line Items]
Line of credit facility, borrowing capacity		100,000,000			100,000,000			$ 100,000,000
Recourse Indebtedness | Secured warehouse facilities | Maximum
Debt Instrument [Line Items]
Contractual Maturity, month and year								2018-07			2018-01
Recourse Indebtedness | Secured warehouse facilities | Minimum
Debt Instrument [Line Items]
Contractual Maturity, month and year								2017-11			2017-11
Recourse Indebtedness | One Year Secured Warehouse Facilities | Secured warehouse facilities
Debt Instrument [Line Items]
Unpaid Principal Balance		0			0			$ 0
Line of credit facility, borrowing capacity		25,000,000			25,000,000			$ 25,000,000					$ 150,000,000
Debt instrument, financial covenant compliance								As of June 30, 2017, we were in compliance with all financial covenants contained in the $25,000 secured warehouse facility.
Non-recourse indebtedness
Debt Instrument [Line Items]
Unpaid Principal Balance		1,232,908,000			1,232,908,000			$ 1,232,908,000			$ 1,376,474,000
Contractual Maturity, month and year								2016-06
Number of mortgage liens properties | Property								5
Non-recourse indebtedness | R A I T F L Seven
Debt Instrument [Line Items]
Outstanding principal balance of classes of investment grade senior notes				$ 276,894,000
Non-recourse indebtedness | CMBS securitizations
Debt Instrument [Line Items]
Unpaid Principal Balance		721,441,000	[3]		721,441,000	[3]		$ 721,441,000	[3]		647,921,000	[4]
Underlying collateral		870,085,000			870,085,000			870,085,000			$ 789,421,000
Non-recourse indebtedness | CMBS securitizations | R A I T F L Three
Debt Instrument [Line Items]
Underlying collateral		0			0			0
Non-recourse indebtedness | CMBS securitizations | R A I T F L Four
Debt Instrument [Line Items]
Unpaid Principal Balance		62,894,000			62,894,000			62,894,000
Underlying collateral		104,284,000			104,284,000			104,284,000
Non-recourse indebtedness | CMBS securitizations | R A I T F L Four | Junior Notes
Debt Instrument [Line Items]
Owned unrated classes of junior notes		41,390,000			41,390,000			41,390,000
Non-recourse indebtedness | CMBS securitizations | R A I T F L Five
Debt Instrument [Line Items]
Unpaid Principal Balance		187,102,000			187,102,000			187,102,000
Underlying collateral		247,905,000			247,905,000			247,905,000
Owned unrated classes of junior notes		$ 60,803,000			$ 60,803,000			$ 60,803,000
Interest in joint venture		60.00%			60.00%			60.00%
Non-recourse indebtedness | CMBS securitizations | R A I T F L Six
Debt Instrument [Line Items]
Underlying collateral		$ 235,823,000			$ 235,823,000			$ 235,823,000
Interest in joint venture																	60.00%
Proceeds from contribution of junior notes																	$ 16,893,000
Non-recourse indebtedness | CMBS securitizations | R A I T F L Six | Junior Notes
Debt Instrument [Line Items]
Owned unrated classes of junior notes		41,272,000			41,272,000			41,272,000
Non-recourse indebtedness | CMBS securitizations | R A I T F L Six | Investment Grade Senior Notes
Debt Instrument [Line Items]
Unpaid Principal Balance		194,551,000			194,551,000			$ 194,551,000
Non-recourse indebtedness | Maximum | CMBS securitizations
Debt Instrument [Line Items]
Contractual Maturity, month and year								2037-06	[3]		2031-12	[4]
Non-recourse indebtedness | Minimum | CMBS securitizations
Debt Instrument [Line Items]
Contractual Maturity, month and year								2031-01	[3]		2031-05	[4]
Non-recourse indebtedness | Loans payable on real estate
Debt Instrument [Line Items]
Unpaid Principal Balance		135,123,000	[5]		135,123,000	[5]		$ 135,123,000	[5]		$ 186,237,000	[6]
Contractual Maturity, month and year								2017-04
Line of credit facility, repayments								$ 22,981,000
Number of real estate properties disposed | Property								3
Gains (losses) on extinguishments of debt								$ 3,813,000
Number of real estate properties disposed less than indebtedness | Property								2
Non-recourse indebtedness | Loans payable on real estate | Industrial real estate properties
Debt Instrument [Line Items]
Unpaid Principal Balance		54,475,000			54,475,000			$ 54,475,000			81,941,000
Non-cash loss on deconsolidation of properties								$ 15,947,000
Number of industrial real estate properties deconsolidated | Property								10
Deconsolidation of properties, carrying value		38,516,000			38,516,000			$ 38,516,000			$ 82,501,000
Number of mortgage liens properties | Property								5
Mortgage liens properties aggregate carrying value								$ 43,414,000
Extinguishment of debt								$ 27,467,000
Remaining number of industrial real estate properties | Property								5
Non-recourse indebtedness | Loans payable on real estate | Maximum
Debt Instrument [Line Items]
Contractual Maturity, month and year								2021-12	[5]		2021-12	[6]
Non-recourse indebtedness | Loans payable on real estate | Minimum
Debt Instrument [Line Items]
Contractual Maturity, month and year								2016-06	[5]		2016-06	[6]
Investment Grade Senior Notes | R A I T F L Seven
Debt Instrument [Line Items]
Real estate investment		$ 276,894,000			$ 276,894,000			$ 276,894,000
Advance rate				80.90%
Convertible notes redemption period One | Recourse Indebtedness | 7.0% convertible senior notes
Debt Instrument [Line Items]
Convertible senior notes redemption period								2021-04
Convertible notes redemption period One | Recourse Indebtedness | 4.0% convertible senior notes
Debt Instrument [Line Items]
Convertible senior notes redemption period								2018-10
Convertible notes redemption period Two | Recourse Indebtedness | 7.0% convertible senior notes
Debt Instrument [Line Items]
Convertible senior notes redemption period								2026-04
Convertible notes redemption period Two | Recourse Indebtedness | 4.0% convertible senior notes
Debt Instrument [Line Items]
Convertible senior notes redemption period								2023-10
Convertible notes redemption period Three | Recourse Indebtedness | 4.0% convertible senior notes
Debt Instrument [Line Items]
Convertible senior notes redemption period								2028-10

[1] Our 7.0% convertible senior notes are redeemable at par, at the option of the holder, in April 2021, and April 2026.

[2] Our 4.0% convertible senior notes are redeemable at par, at the option of the holder, in October 2018, October 2023, and October 2028.

[3] Collateralized by $870,085 principal amount of commercial mortgage loans and participation interests. These obligations were issued by separate legal entities and consequently the assets of the special purpose entities that collateralize these obligations are not available to our creditors.

[4] Collateralized by $789,421 principal amount of commercial mortgage loans and participation interests. These obligations were issued by separate legal entities and consequently the assets of the special purpose entities that collateralize these obligations are not available to our creditors.

[5] One loan payable on real estate had a maturity date of June 2016. This loan is currently in default and is in the process of foreclosure. One loan payable on real estate had a maturity date of April 2017. This loan is currently in default and is in the process of foreclosure.

[6] One loan payable on real estate had a maturity date of June 2016. This loan is currently in default and is in the process of foreclosure.