Statement of Financial Condition of VIEs Reflected in Consolidated Statements of Financial Condition (Detail) - USD ($) $ in Thousands		Jun. 30, 2017		Dec. 31, 2016		Jun. 30, 2016	Dec. 31, 2015
ASSETS
Cash and cash equivalents		$ 700,692	[1],[2]	$ 1,539,746	[2],[3]	$ 2,735,250	$ 1,769,258
Commercial real estate debt investments	[4]	3,972,560	[1]	4,321,739	[3]
Residential mortgages loans	[5]	779,685	[1]	342,289	[3]
Mortgage servicing rights		605,653	[1]	652,216	[3]
Other assets		399,456	[1]	333,063	[3]
Total assets		84,976,578	[1]	87,905,046	[3]
Liabilities
Other secured financing		3,785,543	[1]	3,884,708	[3]
Other derivatives, at fair value		99,380		86,437
Accrued interest payable		185,720	[1]	163,013	[3]
Total liabilities		72,367,153	[1]	75,329,074	[3]
Consolidated VIEs
ASSETS
Cash and cash equivalents		37,900	[1]	23,200	[3]
Residential mortgages loans		150,900	[1]	165,900	[3]
Consolidated VIEs | FREMF Trusts
ASSETS
Commercial real estate debt investments		3,664,092		3,890,807
Accrued interest receivable		9,661		8,690
Other assets				138
Total assets		3,673,753		3,899,635
Liabilities
Securitized debt (non-recourse) at fair value		3,396,885		3,609,164
Accrued interest payable		4,588		4,350
Total liabilities		3,401,473		3,613,514
Consolidated VIEs | Residential Mortgage Loan Trust
ASSETS
Residential mortgages loans		150,859		165,869
Accrued interest receivable		754		836
Total assets		151,613		166,705
Liabilities
Securitized debt (non-recourse) at fair value		41,790		46,638
Accrued interest payable		95		107
Accounts payable and other liabilities		71		662
Total liabilities		41,956		47,407
Consolidated VIEs | Mortgage Servicing Rights Silos
ASSETS
Cash and cash equivalents		37,901		23,198
Residential mortgages loans		13,979		8,309
Mortgage servicing rights		605,653		652,216
Other derivatives, at fair value				9
Other assets		32,721		35,540
Total assets		690,254		719,272
Liabilities
Other secured financing		7,659		3,825
Other derivatives, at fair value		11		9
Accounts payable and other liabilities		4,017		14,007
Total liabilities		$ 11,687		$ 17,841

[1] As a result of a change to a clearing organization's rulebook effective January 3, 2017, beginning with the first quarter 2017 and in subsequent periods the Company is presenting the fair value of centrally cleared interest rate swaps net of variation margin pledged under such transactions. The variation margin was previously reported under cash and cash equivalents and is currently reported as a reduction to interest rate swaps, at fair value. Balances reported prior to the effective date balances will not be adjusted.

[2] Includes cash of consolidated VIEs of $37.9 million and $23.2 million at June 30, 2017 and December 31, 2016, respectively.

[3] Derived from the audited consolidated financial statements at December 31, 2016.

[4] Includes senior securitized commercial mortgage loans of consolidated VIEs carried at fair value of $3.7 billion and $3.9 billion at June 30, 2017 and December 31, 2016, respectively.

[5] Includes securitized residential mortgage loans of a consolidated VIE carried at fair value of $150.9 million and $165.9 million at June 30, 2017 and December 31, 2016, respectively.