Loans Receivable, Net and Allowance for Credit Losses on Loans - Summary of Loan Modifications Made to Borrowers Experiencing Financial Difficulty (Detail) - Real Estate Loans [Member] - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023
Financing Receivable, Modified [Line Items]
Amortized Cost Basis	$ 71
Residential [Member]
Financing Receivable, Modified [Line Items]
Amortized Cost Basis	$ 71	$ 54
% of Total Class of Financing Receivable	0.01%
Reduced weighted-average contractual interest rate	5.00%		7.25%
Extended term	360 months