Variable Interest Entities - Carrying Value for Residential Mortgage Loans (Detail) - USD ($) $ in Thousands		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Variable Interest Entity [Line Items]
Carrying value	[1]	$ 458,348		$ 549,016
Residential Mortgage Backed Securities
Variable Interest Entity [Line Items]
Principal balance		148,908		11,281
Unamortized premium, net of discount		4,014		379
Carrying value		152,922		11,660
Variable Interest Entities Primary Beneficiary | Residential Mortgage Backed Securities
Variable Interest Entity [Line Items]
Principal balance		456,768		545,881
Unamortized premium, net of discount		1,755		3,321
Allowance for loan losses		(175)		(186)		$ (203)
Carrying value		$ 458,348	[1]	$ 549,016	[1]	$ 639,351

[1] The consolidated balance sheets include assets of consolidated variable interest entities, or VIEs, that can only be used to settle obligations and liabilities of the VIEs for which creditors do not have recourse to the Company. At December 31, 2019 and December 31, 2018, total assets of the consolidated VIEs were $460 million and $551 million (including accrued interest receivable of $1.5 million and $1.8 million), respectively (which is recorded above in the line item “Interest and dividends receivable”), and total liabilities were $450 million and $541 million (including accrued interest payable of $1.4 million and $1.7 million), respectively (which is recorded above in the line item “Accrued interest payable”). Please refer to Note 5, “Variable Interest Entities,” for further discussion.