Fair Value of Financial Instruments (Aggregate Fair Value And Remaining Contractual Principal Balance Outstanding On Fair Value Option) (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Residential Mortgage Loans [Member] | Loans Receivable [Member]
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Loans receivable and other instruments, contractual outstanding principal	$ 18	$ 39
Loans receivable and other instruments, 90 days or more past due, contractual outstanding principal	57	149
Loans receivable and other instruments, fair value	18	39
Loans receivable and other instruments, 90 days or more past due, fair value	14	39
Loans receivable and other instruments, difference	0	0
Loans receivable and other instruments, 90 days or more past due, difference	43	110
Total Loans Receivable and Other Instruments [Member] | Loans Receivable [Member]
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Loans receivable and other instruments, contractual outstanding principal	75	188
Loans receivable and other instruments, fair value	32	78
Loans receivable and other instruments, difference	43	110
Variable Interest Entity Notes [Member]
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Long-term debt instruments, contractual outstanding principal	329	780
Long-term debt instruments, fair value	78	172
Long-term debt instruments, difference	251	608
Medium Term Notes [Member]
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Long-term debt instruments, contractual outstanding principal	53	53
Long-term debt instruments, fair value	37	41
Long-term debt instruments, difference	$ 16	$ 12