Fair Value of Financial Instruments (Aggregate Fair Value And Remaining Contractual Principal Balance Outstanding On Fair Value Option) (Detail) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
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	$ 14	$ 18
Loans receivable and other instruments, 90 days or more past due, contractual outstanding principal	50	58
Loans receivable and other instruments, fair value	14	18
Loans receivable and other instruments, 90 days or more past due, fair value	16	17
Loans receivable and other instruments, difference	0	0
Loans receivable and other instruments, 90 days or more past due, difference	34	41
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	64	76
Loans receivable and other instruments, fair value	30	35
Loans receivable and other instruments, difference	34	41
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	46	328
Long-term debt instruments, fair value	32	78
Long-term debt instruments, difference	14	250
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	56	55
Long-term debt instruments, fair value	36	40
Long-term debt instruments, difference	$ 20	$ 15