Commercial Real Estate Investments - Additional Information (Detail)	1 Months Ended					3 Months Ended			6 Months Ended			12 Months Ended
	Apr. 30, 2016 USD ($)	Feb. 29, 2016 USD ($) Loan	Apr. 30, 2015 USD ($) Loan	Feb. 28, 2015 USD ($) Loan	Jan. 31, 2014 USD ($)	Jun. 30, 2016 USD ($)		Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) Property		Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)		Dec. 11, 2015 USD ($)	Nov. 30, 2015 Property
Commercial Real Estate [Line Items]
Sales of senior loan												$ 46,945,000
Allowance for loan losses									$ 0			0
Weighted average amortization period for intangible assets and liabilities									4 years 7 months 6 days
Depreciation expense									$ 10,684,000		$ 5,687,000
Securitization financing transaction, purchase					$ 399,500,000
Securitization financing transaction, total					$ 260,700,000	$ 3,748,289,000	[1]		3,748,289,000	[1]		2,540,711,000	[1],[2]
Securitization financing transaction, weighted average rate					65.30%
Securitization cost					$ 4,300,000
Carrying value of trust's liabilities						59,300,000			59,300,000
Senior Secured mortgages of Consolidated VIE						187,200,000			187,200,000			262,700,000	[2]
Unamortized origination fees						100,000			100,000
Deferred financing costs						100,000			100,000
Other Operating Income (Expense) [Member]
Commercial Real Estate [Line Items]
Depreciation expense						6,100,000		$ 2,900,000	10,700,000		$ 5,700,000
FREMF Trust
Commercial Real Estate [Line Items]
Exposure to the obligations of the VIE limited to the amount of investment						298,200,000			298,200,000
Gain (Loss) recognized upon initial consolidation									0
Debt issue costs expensed									200,000			800,000
Mortgage loans, unpaid principal balance						4,000,000,000			4,000,000,000
Loans 90 days or more past due or on nonaccrual status						0			0
Gain (Loss) attributable to instrument- specific credit risk									0
Freddie Mac | FREM 2016-KLH1 [Member] | FREMF Trust
Commercial Real Estate [Line Items]
Face value		$ 107,600,000
Variable interest entity, consolidated, carrying amount, assets						1,500,000,000			1,500,000,000
Variable interest entity, consolidated, carrying amount, liabilities						1,400,000,000			1,400,000,000
Payment to purchase mortgage loans		107,600,000
Discounted value		$ 4,400,000
Freddie Mac | FREMF 2015-KLSF [Member] | FREMF Trust
Commercial Real Estate [Line Items]
Variable interest entity, consolidated, carrying amount, assets						1,300,000,000			1,300,000,000
Variable interest entity, consolidated, carrying amount, liabilities						1,200,000,000			1,200,000,000
Payment to purchase mortgage loans				$ 102,100,000
Freddie Mac | FREMF 2015-KF07 | FREMF Trust
Commercial Real Estate [Line Items]
Variable interest entity, consolidated, carrying amount, assets						1,100,000,000			1,100,000,000
Variable interest entity, consolidated, carrying amount, liabilities						1,000,000,000			1,000,000,000
Payment to purchase mortgage loans			$ 89,400,000
Freddie Mac | Floating Rate Multifamily Mortgage Loans [Member] | FREM 2016-KLH1 [Member]
Commercial Real Estate [Line Items]
Number of loans in the underlying portfolio | Loan		28
Face value		$ 1,500,000,000
Freddie Mac | Floating Rate Multifamily Mortgage Loans [Member] | FREMF 2015-KLSF [Member]
Commercial Real Estate [Line Items]
Number of loans in the underlying portfolio | Loan				11
Face value				$ 1,400,000,000
Freddie Mac | Floating Rate Multifamily Mortgage Loans [Member] | FREMF 2015-KF07
Commercial Real Estate [Line Items]
Number of loans in the underlying portfolio | Loan			40
Face value			$ 1,200,000,000
Commercial Mortgage
Commercial Real Estate [Line Items]
Outstanding impaired loans, nonaccrual loans, and loans in default						0			0			0
Allowance for loan losses									0			0
Commercial Mortgage | Mezzanine Loans
Commercial Real Estate [Line Items]
Allowance for loan losses									$ 0			0
Multi Tenant Retail
Commercial Real Estate [Line Items]
Number of multi-tenant retail properties acquired | Property															11
Total purchase price						132,000,000
Additional depreciation and amortization						4,200,000
Number of non-core properties sold | Property									3
Non-core properties sold									$ 12,800,000
Gain on sale of non-core properties									$ 800,000
Commercial Mortgage Trust Mo One [Member]
Commercial Real Estate [Line Items]
Securitization financing transaction, variable interest rate					1.74%
Securitization financing transaction, variable interest rate description									LIBOR plus 1.74% at closing
Commercial Mortgage Loan [Member]
Commercial Real Estate [Line Items]
Debt issued						$ 331,046,000			$ 331,046,000			338,444,000
CALIFORNIA | Multi Tenant Retail
Commercial Real Estate [Line Items]
Total purchase price									37,750,000
CALIFORNIA | Commercial Mortgage Loan [Member] | Eight Class AB Office Properties In Orange Country California [Member]
Commercial Real Estate [Line Items]
Funding for senior mortgage loan, net of origination fees												278,600,000
Future funding commitment												30,000,000
Funding for senior mortgage loan, net of origination fees												280,000,000
Debt issued														$ 335,000,000
CALIFORNIA | Commercial Mortgage Loan [Member] | Eight Class AB Office Properties In Orange Country California [Member] | Mezzanine Loans
Commercial Real Estate [Line Items]
Funding for senior mortgage loan, net of origination fees												52,700,000
Debt issued												$ 55,000,000
CALIFORNIA | Commercial Mortgage Loan [Member] | Senior Loans | Eight Class AB Office Properties In Orange Country California [Member]
Commercial Real Estate [Line Items]
Funding for senior mortgage loan, net of origination fees	$ 114,300,000								164,200,000
Sales of senior loan	115,000,000
Gain on sales of senior loan	$ 0
Remains senior loan held for sale									$ 165,000,000

[1] Includes securitized debt of consolidated VIEs carried at fair value of $3.7 billion and $2.4 billion at June 30, 2016 and December 31, 2015, respectively.

[2] Derived from the audited consolidated financial statements at December 31, 2015.